Fix links to outdated 'master' in RTD.

ReadTheDocs hosts master (dev branch) docs under /latest.
(Old /master was not building regularly.)

README.rst

@@ -42,7 +42,7 @@ Djrill is released under the BSD license. It is tested against Django 1.3---1.6
 
 **Resources**
 
-* Full documentation: https://djrill.readthedocs.org/en/master/
+* Full documentation: https://djrill.readthedocs.org/en/latest/
 * Package on PyPI: https://pypi.python.org/pypi/djrill
 * Project on Github: https://github.com/brack3t/Djrill
 
@@ -110,5 +110,5 @@ Djrill 1-2-3
 .. END quickstart
 
 
-See the `full documentation <https://djrill.readthedocs.org/en/master/>`_
+See the `full documentation <https://djrill.readthedocs.org/en/latest/>`_
 for more features and options.

setup.py

@@ -12,7 +12,7 @@ def long_description_from_readme(rst):
     # In release branches, freeze some external links to refer to this X.Y version:
     if not "dev" in __version__:
         rst = re.sub(r'branch=master', 'branch=v' + __minor_version__, rst)  # Travis build status
-        rst = re.sub(r'/master', '/v' + __minor_version__, rst)  # ReadTheDocs
+        rst = re.sub(r'/latest', '/v' + __minor_version__, rst)  # ReadTheDocs
     return rst
 
 with open('README.rst') as f: