Add 3.1 release manifest

[torcolvin]

Should I also add a file for

manifest/3.1/3.1.0.xml with duplicate contents of 3.1.xml or leave that to the inevitable 3.1.1 point release?

I was going to merge this change into the release branch AND master.

[bbrks]

• 3.1.0.xml comes only when we have a new 3.1.x release (otherwise you'd end up with 2 3.1.0 manifests)
• Nothing reads the branch version of product-config.json - master is the source of truth for what versions to build. Changing this isn't nessesary.
• We can get the 3.1.0.xml into the release branch for our weird Jenkins jobs that depend on the release branch - but the build team's jobs read the master version.

[torcolvin]

• Nothing reads the branch version of product-config.json - master is the source of truth for what versions to build. Changing this isn't nessesary.

Do you prefer to have release branch match master? Is it correct in theory that none of this needs to be done on the release branch?

[bbrks]

A couple of things (these are in the doc)

[bbrks]

the revision was added in the wrong place in the manifest