proto: Consider lightweight Git tags when determining the version number and strip initial "v" from Git tag names

By default, git describe only uses annotated tags. However, most projects use non-annotated or "lightweight" tags instead of annotated ones. Include the --tags flag in the example to consider all tag types.

Many projects use tags that are the version number prefixed with "v". In particular, GitHub suggests and encourages this naming convention. Include code in the example to remove the "v" so that the VCS package version number is comparable to the regular package version number.