Add GitHub action to check links

[julienloizelet]

Hi,
this pull request add a GitHub actions to check links in the README.

This is just a check with the awesome-bot.

I tried it on my fork, and you can see the result here

There is only a 404, lot of 301 because of en ending /, some 302 and 303, and some duplicates URL (called dupes).

For the moment, I call awesome_bot README.md --skip-save-results but we could easily add other options :

• --allow-dupe Duplicate URLs are allowed
• --white-list [urls] Comma separated URLs to white list
• --allow [errors] Status code errors to allow
• --allow-redirect Redirected URLs are allowed

etc, etc. (please see the doc in the awesome_bot repo).

Of course, we could also change the on part of the action (I set it to push, pull_request and workflow_dispatch, but we may prefer something else)

Let me know what you think :)

[rfay]

Thanks, we'll give it a shot. If it ends up being too annoying (have had some trouble with link checking timeouts and such in ddev, can be a bit of work)

[rfay]

Now you can do a PR to do the fixups :) Thanks!