Display "generated with <commit sha>" in the footer

[st0012]

I think it'd be beneficial for both the doc writer and consumer to be able to tell the version of the doc directly from the web page.

[t-mangoe]

Hi! I'm interested in this issue (as my first contribution to rdoc). If possible, I am considering making a contribution. Is it the Git hash that should be displayed in the footer?

[st0012]

Yes. So to properly support this feature, RDoc needs to:

• Check if the project uses git
  • If not, don't display that section at all
• Use a safe way to fetch the current commit sha
  • We may also want to consider other info, like branch/tag name when applicable, and perhaps date too?

[t-mangoe]

@st0012 Thank you for your comment! I'm considering using the “git” gem to fetch the current commit sha. In this way, we can check if the project uses git, and we may get other git information. Adding a gem might be a concern... What do you think?