fix links in dev_doc

doc/dev_start_guide.txt

@@ -11,13 +11,13 @@ You want to contribute to Theano? That is great! This page explain our
 workflow and some resource for doing so.
 
 Looking for an idea for a first contribution? Check `github issue
-<https://github.com/Theano/Theano/issues?q=is%3Aopen+is%3Aissue+label%3A%22Easy+fix%22>`
+<https://github.com/Theano/Theano/issues?q=is%3Aopen+is%3Aissue+label%3A%22Easy+fix%22>`_
 with a label ``easy fix``. They are good starter. It is recommanded
 that you write on the issue you want to work on it. This help make
 sure it is up to date and see if nobody else is working on it. Also,
 we can sometimes provides more information about it.  There is also
 the label `NeedSomeoneToFinish
-<https://github.com/Theano/Theano/labels/NeedSomeoneToFinish>` that is
+<https://github.com/Theano/Theano/labels/NeedSomeoneToFinish>`_ that is
 interresting to check. The difficulty level is variable.
 
 Resources