docs: Added demo possibility.

[MishaJexia]

Summary
This PR adds Runme button-label to run the project from latest commit with one click.

How it works:

1. Runme clones the repository and builds a docker image for latest commit;
2. deploys docker image to k8s cluster;
3. creates domain with SSL certificate;
4. shows web application;
5. destroys app instance after 10 minutes.

You can find detailed information on how this works here. The small demo you can find here.

Why we would like to offer change?

• We like and use vuepress and want to add a demo opportunity to the repo.
• Runme is perfect solution to demonstrate the current state of code/repository, anybody can just click the button and see the state;
• Runme totally free, we love open source projects and want to support them;
• Runme has only one limit: you can run one commit no more than once every 5 minutes;

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Docs
• Build-related changes
• Other, please describe: demo runner for repo.

If changing the UI of default theme, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

You have tested in the following browsers: (Providing a detailed version will be better.)

• Chrome
• Firefox
• Safari
• Edge
• IE

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature
• Related documents have been updated
• Related tests have been updated

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

Other information:
Regarding any future questions, you can contact jexia.com

[MishaJexia]

Hey there, any additional action is needed maybe?
Cheers