Update docs building
Update docs building:
* Switch to sphinx-build
* Update requirements for Sphinx and openstackdocstheme for
python 3, create doc/requirements.txt file.
* Remove unneeded doc and translation sections from setup.cfg
* Remove install_command, it's unneeded, the default is fine.
* Use TOX_CONSTRAINTS instead of obsolete UPPER_CONSTRAINTS
Change-Id: I6ff4427014fc967a6f7b28fc6cbe5a0f4eca601c
diff --git a/doc/requirements.txt b/doc/requirements.txt
new file mode 100644
index 0000000..72d01e9
--- /dev/null
+++ b/doc/requirements.txt
@@ -0,0 +1,4 @@
+sphinx>=2.0.0,!=2.1.0 # BSD
+openstackdocstheme>=2.0.0 # Apache-2.0
+
+reno>=2.5.0 # Apache-2.0