Document branching strategy for public repos

[mattheworiordan]

See ably/ably-python#134 (comment)

Whilst we have internal docs on branching and more generally our git workflows, this documentation is lacking for public contributors. We should make this publicly available. As the Wiki is private, we should add a new page to our docs site, under https://docs.ably.io/client-lib-development-guide/

┆Issue is synchronized with this Jira Task by Unito

[mattheworiordan]

In addition, we should review all public (and private) repos that don't follow the new strategy and ensure they are using the correct git workflow.

[QuintinWillison]

I'll pick this up, in light of recent internal communications on this matter.

[sync-by-unito]

➤ Automation for Jira commented:

The link to the corresponding Jira issue is https://ably.atlassian.net/browse/SDK-2806