Update README main title and display preview video (#7037)

* Update main title in README

* Remove extra colon character

* Remove horizontal rules in README

Headings should suffice.

* Display demo video in README

This way, users can have a chance to have a quick preview of odo.

README.md

@@ -1,4 +1,4 @@
-`odo` - Developer-focused CLI for fast & iterative application development on Kubernetes
+`odo` - Fast, Iterative and Simplified container-based application development
 ---
 
 [![GitHub release](https://img.shields.io/github/v/release/redhat-developer/odo?style=for-the-badge)](https://github.com/redhat-developer/odo/releases/latest)
@@ -8,8 +8,6 @@
 
 ![logo](/docs/website/static/img/logo_small.png)
 
-----
-
 ### Overview
 
 `odo` is a fast, and iterative CLI tool for container-based application development.
@@ -18,7 +16,7 @@ It is an implementation of the open [Devfile](https://devfile.io/) standard, sup
 **Why use `odo`?**
 
 * **Easy onboarding:** By auto-detecting the project source code, you can easily get started with `odo`.
-* **No cluster needed:**: With Podman support, having a Kubernetes cluster is not required to get started with `odo`. Using a common abstraction, `odo` can run your application on Podman, Kubernetes or OpenShift.
+* **No cluster needed**: With Podman support, having a Kubernetes cluster is not required to get started with `odo`. Using a common abstraction, `odo` can run your application on Podman, Kubernetes or OpenShift.
 * **Fast:** Spend less time maintaining your application deployment infrastructure and more time coding. Immediately have your application running each time you save.
 * **Standalone:** `odo` is a standalone tool that communicates directly with the container orchestrator API.
 * **No configuration needed:** There is no need to dive into complex Kubernetes YAML configuration files. `odo` abstracts those concepts away and lets you focus on what matters most: code.
@@ -27,20 +25,19 @@ It is an implementation of the open [Devfile](https://devfile.io/) standard, sup
 
 Learn more about the features provided by `odo` on [odo.dev](https://odo.dev/docs/overview/features).
 
-----
+### Demo
+
+[//]: # (URL obtained using the preview URL generated by GitHub from the source video in /docs/website/static/video/odo-preview-with-podman.hd.webm - see https://github.blog/2021-05-13-video-uploads-available-github/)
+[odo demo.webm](https://github.com/redhat-developer/odo/assets/593208/815f77a2-be43-4763-961b-204c88fb2cce)
 
 ### Installing `odo`
 
 Please check the [installation guide on odo.dev](https://odo.dev/docs/overview/installation/).
 
-----
-
 ### Official documentation
 
 Visit [odo.dev](https://odo.dev/) to learn more about odo.
 
-----
-
 ### Community, discussion, contribution, and support
 
 #### Chat 
@@ -68,8 +65,6 @@ All our calls are open to public. You are welcome to join any of our calls.
 
 You can find the exact dates of all scheduled team calls together with sprint dates in the [google calendar](https://calendar.google.com/calendar/embed?src=gi0s0v5ukfqkjpnn26p6va3jfc%40group.calendar.google.com) ([iCal format](https://calendar.google.com/calendar/ical/gi0s0v5ukfqkjpnn26p6va3jfc%40group.calendar.google.com/public/basic.ics)).
 
-----
-
 ### Legal
 
 #### License