[SR-15314] [Swift-DocC] Improve help information for docc index command

[ethan-kusters]

Previous ID	SR-15314
Radar	rdar://68701016
Original Reporter	@ethan-kusters
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Swift-DocC
Labels	Bug, StarterBug
Assignee	maldahleh (JIRA)
Priority	Medium

md5: c4c6583d1092b3d462a1a4eacca43836

Issue Description:

The help information emitted for the docc index subcommand instructs the user to provide a .docc catalog as input. The command actually expects a Data folder of render JSON files from a compiled documentation archive. We should update the help information to reflect this.

Currently this is what docc emits for ‘docc index --help’:

OVERVIEW: Create an index for the documentation from compiled data.

USAGE: docc index <source-bundle-path> -bundle-identifier <bundle-identifier> [-verbose]

ARGUMENTS:
<source-bundle-path> Path to a documentation bundle directory.
The '.docc' bundle docc will build.

[d-ronnqvist]

The PR that fix this issue was merged here #10