bitbake: bitbake-user-manual: add reference to bitbake git repository

In the HTML page footer.

(Bitbake rev: 897f238e5e34d3f8f23e3b7ac8a19ef8bb0aca22)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/doc/_templates/footer.html

@@ -0,0 +1,9 @@
+<footer>
+  <hr/>
+  <div role="contentinfo">
+    <p>&copy; Copyright {{ copyright }}
+       <br>Last updated on {{ last_updated }} from the <a href="https://git.openembedded.org/bitbake/">bitbake</a> git repository.
+    </p>
+  </div>
+</footer>
+