v3: doc: Add returns and possible exceptions to API

Add description of returned types and possible exceptions generated by
Chamelond V3 API.

BUG=b:269787264
TEST=None

Change-Id: I068eb51e70b6e3fdfb9a1b46b2b47696e8bfc62c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/5545460
Commit-Queue: Tomasz Michalec <tmichalec@google.com>
Tested-by: Tomasz Michalec <tmichalec@google.com>
Reviewed-by: Michał Headcrab Crowbar Barnaś <barnas@google.com>
1 file changed