Spelling fixes.

doc/index.txt

@@ -106,7 +106,7 @@ Community
 
 * Register and post to `theano-dev`_ if you want to talk to the developers.
 
-* Register to `theano-github`_ if you want to receive an email for all change to the github repository.
+* Register to `theano-github`_ if you want to receive an email for all changes to the GitHub repository.
 
 * Register to `theano-buildbot`_ if you want to receive our daily buildbot email.
 

doc/internal/dev_start_guide.txt

@@ -40,8 +40,8 @@ style, but as we modify the code, we update it accordingly.
 Mailing list
 ------------
 
-See the theano main page for the theano-dev, theano-buildbot and
-theano-github mailing list. They are usefull to Theano contributor's.
+See the Theano main page for the theano-dev, theano-buildbot and
+theano-github mailing list. They are useful to Theano contributors.
 
 Typical development workflow
 ----------------------------
@@ -196,12 +196,12 @@ email to the `theano-buildbot`_ mailing list.
 
 For more detail, see :ref:`see <metadocumentation_nightly_build>`.
 
-To run all the test with the same configuration as the buildbot, run this script:
+To run all the tests with the same configuration as the buildbot, run this script:
 
 .. code-block:: bash
 
    theano/misc/do_nightly_build
 
-This function accept argument that it forward to nosetests. So you can
+This function accepts arguments that it forward to nosetests. You can
 run only some tests or enable pdb by giving the equivalent nosetests
 parameters.