Master list of repositories

[avishnu]

Update the parent readme.md files of openebs/community and openebs/openebs with a list which contains:

• Name (link) of each active repo in the current org
• Purpose of each active repo
• Engine(s) or Utility(ies) the repo belongs to

[orville-wright]

Lets make this a separate new page by itself (under each parent repo).
The parent repos now have a lot of info in them and they're getting a bit long. .. and this repo list could have a lot of technical info surrounding / supporting it. Which will add to the length of the parent repo readme if it were included in that file.

[orville-wright]

Decisions

1 Location: move into Community repo root
2. Name of new file: REPOSITORIES.md
3. put quick link on main repo home page

@avishnu