Merge pull request #4503 from asottile/upgrade

Upgrade sphinx doc requirements

Author: RonnyPfannschmidt

doc/en/requirements.txt

@@ -1,5 +1,3 @@
-pygments-pytest>=1.0.4
-# pinning sphinx to 1.4.* due to search issues with rtd:
-# https://github.com/rtfd/readthedocs-sphinx-ext/issues/25
-sphinx ==1.4.*
+pygments-pytest>=1.1.0
+sphinx>=1.8.2
 sphinxcontrib-trio