Link Sphinx manpage references to online Git docs

(This is grouped as a general option since it is technically
classified as such, even though it currently only affects HTML
output.)

Author: EliahKagan

Diff for: doc/source/conf.py

@@ -87,6 +87,8 @@
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = "sphinx"
 
+manpages_url = "https://git-scm.com/docs/{page}"
+
 
 # Options for HTML output
 # -----------------------