Missing docs

[kfsone]

Documentation is missing for: annotate, substitute repository and substitute branch, and decoding what they do is a little hard.

[Vampire]

annotate => create annotated tags, not lightweight tags

substitue branch and substitue repository can be a sed-like substitution expression like s/foo/bar/ to substitue bar for foo or s| |_| to substitute underscores for spaces.
This can e. g. be used to rename branches that have valid names in SVN but would have illegal names in Git.