docs: repo-hooks: fix cwd details
docs: repo-hooks: fix cwd details

The hooks are run from the top of the manifest checkout, not from the
individual git repos.  It's up to individual hooks to chdir as needed.

Change-Id: I53325e0c3dcaa9c250b02b223e78d238d2cbd36d

lipro-yocto/git-repo,codetutil/git-repo,aosp-mirror/tools_repo,GerritCodeReview/git-repo,couchbasedeps/git-repo,couchbasedeps/git-repo,codetutil/git-repo,lipro-yocto/git-repo,mer-tools/git-repo,lewixliu/git-repo,TheQtCompany/git-repo,mer-tools/git-repo,chenzilin/git-repo,gabbayo/git-repo,GerritCodeReview/git-repo,TheQtCompany/git-repo,aosp-mirror/tools_repo,chenzilin/git-repo,gabbayo/git-repo,lewixliu/git-repo