Remove Memos broken demo link, update homepage (#3786)

- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/3558
- https://memos.onrender.com/ : HTTP 404
- https://demo.usememos.com/:  This service has been suspended.

README.md

@@ -133,7 +133,7 @@ _Related: [Personal Dashboards](#personal-dashboards)_
 - [Open Web Analytics](http://www.openwebanalytics.com/) - Web analytics framework that lets you stay in control of how you instrument and analyze the use of your websites and applications. ([Source Code](https://github.com/padams/Open-Web-Analytics)) `GPL-2.0` `PHP`
 - [Plausible Analytics](https://plausible.io/) - Simple, open-source, lightweight (< 1 KB) and privacy-friendly web analytics. ([Source Code](https://github.com/plausible/analytics/)) `MIT` `Elixir`
 - [PostHog](https://posthog.com) - Product analytics, session recording, feature flagging and a/b testing that you can self-host. Alternative to Mixpanel/Amplitude/Heap/HotJar/Optimizely. ([Source Code](https://github.com/posthog/posthog)) `MIT` `Python`
-- [Redash](http://redash.io) - Connect and query your data sources, build dashboards to visualize data and share them with your company. ([Demo](https://demo.redash.io), [Source Code](https://github.com/getredash/redash)) `BSD-2-Clause` `Docker`
+- [Redash](http://redash.io) - Connect and query your data sources, build dashboards to visualize data and share them with your company. ([Source Code](https://github.com/getredash/redash)) `BSD-2-Clause` `Docker`
 - [RudderStack](https://rudderstack.com/) - Collect, unify, transform, and store your customer data, and route it to a wide range of common, popular marketing, sales, and product tools. alternative to Segment. ([Source Code](https://github.com/rudderlabs/rudder-server/)) `AGPL-3.0` `Docker/K8S/Go/Nodejs`
 - [Shynet](https://github.com/milesmcc/shynet) - Modern, privacy-friendly, and detailed web analytics that works without cookies or JS. `Apache-2.0` `Python`
 - [Socioboard](https://github.com/socioboard/Socioboard-4.0) `⚠` - Social media management, analytics, and reporting platform supporting nine social media networks out-of-the-box. `GPL-3.0` `Nodejs`
@@ -436,7 +436,7 @@ Simple deployment of [E-mail](https://en.wikipedia.org/wiki/Email) servers, e.g.
 - [Sendmail](https://www.proofpoint.com/us/products/email-protection/open-source-email-solution) - Message transfer agent (MTA). `Sendmail` `C`
 - [Slimta](https://www.slimta.org) - Mail Transfer Library built on Python. ([Source Code](https://github.com/slimta/python-slimta)) `MIT` `Python`
 - [Stalwart SMTP](https://stalw.art/smtp) - Modern SMTP server designed with a focus on security, speed, and extensive configurability. ([Source Code](https://github.com/stalwartlabs/smtp-server)) `AGPL-3.0` `Rust`
-- [vSMTP](https://viridit.com/vsmtp-mail-transfer-agent/) - Next-gen MTA. Secured, Faster and Greener. ([Source Code](https://github.com/viridIT/vSMTP)) `GPL-3.0` `Rust`
+- [vSMTP](https://viridit.com/products/) - Next-gen MTA. Secured, Faster and Greener. ([Source Code](https://github.com/viridIT/vSMTP)) `GPL-3.0` `Rust`
 
 
 ### Communication - Email - Mailing Lists and Newsletters
@@ -1425,7 +1425,7 @@ _Related: [Wikis](#wikis)_
 - [Livebook](https://livebook.dev) - Realtime collaborative notebook app based on Markdown that supports running Elixir codesnippets, TeX and Mermaid Diagrams. Easily deployed using Docker or Elixir. ([Source Code](https://github.com/livebook-dev/livebook)) `Apache-2.0` `Elixir`
 - [Markdown Edit](https://github.com/georgeOsdDev/markdown-edit/) - Online markdown editor/viewer. `MIT` `HTML5`
 - [Meemo](https://meemo.minimal-space.de/) - Personal notes stream with Markdown support. ([Source Code](https://github.com/nebulade/meemo)) `MIT` `Nodejs`
-- [Memos](https://github.com/usememos/memos) - An open source, self-hosted knowledge base that works with a SQLite db file. ([Demo](https://memos.onrender.com/)) `MIT` `Docker/Go`
+- [Memos](https://usememos.com/) - An open source, self-hosted knowledge base that works with a SQLite db file. ([Source Code](https://github.com/usememos/memos)) `MIT` `Docker/Go`
 - [minimalist-web-notepad](https://github.com/pereorga/minimalist-web-notepad) - Minimalist notepad.cc clone. ([Demo](https://notes.orga.cat/)) `Apache-2.0` `PHP`
 - [MiniNote](https://github.com/muety/mininote) - Simple Markdown note-taking app with persistence. `MIT` `Nodejs`
 - [Notes'n'Todos](https://github.com/larspontoppidan/notesntodos) - Write notes and todos online in markdown with tag filtering and date sorting. ([Demo](https://lpss.dk/nnt-playground/)) `MIT` `Python`
@@ -1814,7 +1814,7 @@ _Related: [Software Development - Low Code](#software-development---low-code)_
 - [HttPlaceholder](https://github.com/dukeofharen/httplaceholder) - Quickly mock away any webservice using HttPlaceholder. HttPlaceholder lets you specify what the request should look like and what response needs to be returned. `MIT` `C#`
 - [ICEcoder](https://icecoder.net/) - ICEcoder is a web IDE / browser based code editor, which allows you to develop websites directly within the web browser. ([Demo](http://demo.icecoder.net/ICEcoder/), [Source Code](https://github.com/icecoder/ICEcoder)) `MIT` `PHP`
 - [Judge0 CE](https://judge0.com) - Open source API to compile and run source code. ([Source Code](https://github.com/judge0/judge0)) `GPL-3.0` `Ruby`
-- [JupyterLab](https://jupyterlab.github.io/jupyterlab/) - Web-based environment for interactive and reproducible computing. ([Demo](https://mybinder.org/v2/gh/jupyterlab/jupyterlab-demo/try.jupyter.org?urlpath=lab), [Source Code](https://github.com/jupyterlab/jupyterlab/)) `BSD-3-Clause` `Python/Docker`
+- [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) - Web-based environment for interactive and reproducible computing. ([Demo](https://mybinder.org/v2/gh/jupyterlab/jupyterlab-demo/try.jupyter.org?urlpath=lab), [Source Code](https://github.com/jupyterlab/jupyterlab/)) `BSD-3-Clause` `Python/Docker`
 - [Lowdefy](https://www.lowdefy.com/) - Build internal tools, BI dashboards, admin panels, CRUD apps and workflows in minutes using YAML / JSON on an self-hosted, open-source platform. Connect to your data sources, host via Serverless, Netlify or Docker. ([Source Code](https://github.com/lowdefy/lowdefy)) `Apache-2.0` `Nodejs`
 - [ML Workspace](https://github.com/ml-tooling/ml-workspace) - All-in-one web-based IDE for machine learning and data science. `Apache-2.0` `Docker`
 - [RStudio Server](https://www.rstudio.com/products/rstudio/#Server) - Web browser based IDE for R. ([Source Code](https://github.com/rstudio/rstudio)) `AGPL-3.0` `Java/C++`