Add link to github commit for the spec as per request.

specification/00_basis.rst

@@ -6,7 +6,7 @@ Version: {{spec_version}}
 This specification has been generated from
 https://github.com/matrix-org/matrix-doc using
 https://github.com/matrix-org/matrix-doc/blob/master/scripts/gendoc.py as of
-revision ``{{git_version}}``.
+revision ``{{git_version}}`` - https://github.com/matrix-org/matrix-doc/tree/{{git_rev}}
 
 Changelog
 ~~~~~~~~~

templating/matrix_templates/sections.py

@@ -10,7 +10,10 @@ class MatrixSections(Sections):
 
     # pass through git ver so it'll be dropped in the input file
     def render_git_version(self):
-        return self.units.get("git_version")
+        return self.units.get("git_version")["string"]
+
+    def render_git_rev(self):
+        return self.units.get("git_version")["revision"]
 
     def render_spec_version(self):
         spec_meta = self.units.get("spec_meta")

templating/matrix_templates/units.py

@@ -455,11 +455,14 @@ class MatrixUnits(Units):
         except subprocess.CalledProcessError:
             git_dirty = ""
 
+        git_version = "Unknown"
         if git_branch or git_tag or git_commit or git_dirty:
             git_version = ",".join(
                 s for s in
                 (git_branch, git_tag, git_commit, git_dirty,)
                 if s
-            )
-            return git_version.encode("ascii")
-        return "Unknown rev"
+            ).encode("ascii")
+        return {
+            "string": git_version,
+            "revision": git_commit
+        }