Quick notes for tools release planning

[brodycj]

Platforms affected

All

What does this PR do?

Add quick tools release planning notes to docs/tools-release-process.md

What testing has been done on this change?

• Visual inspection

Checklist

• Reported an issue in the JIRA database
• Commit message follows the format: "CB-3232: (android) Fix bug with resolving file paths", where CB-xxxx is the JIRA ID & "android" is the platform affected.
• Added automated test coverage as appropriate for this change.

[brodycj]

I made this whole change with the Tools release planning section which now has the dependency graph added in GH-186, as a quick way to deal with the following problem: the whole tools-release-planning.md document was written assuming that someone would release all tools packages at once but this is not always what we want.

For the ongoing patch release, which still cannot drop deprecated Node.js 4 version, we know we have to update the packages in a sequential order to avoid duplicate cordova-common dependency.

But this may turn out to be not as bad as I thought once we drop Node.js 4 support, especially if we do start committing package-lock.json in the next major release. If we start using caret (^) in dependencies, so that npm should be smart enough to grab the latest version possible to satisfy package dependencies, then I think this duplicate cordova-common dependency problem should go away.