Fix yaml snippet for sphinx for python3

Something about this yaml snippet was causing:

  Could not lex literal_block as "yaml". Highlighting skipped.

but only when run under python3. I'm guessing something related to
utf-8, although it's not immediately apparent for me locally. I
basically re-typed the name 'tooz-tox-py35-etcd3' and it started
working. Go figure.

Change-Id: Idded1004ffaebe51010fa52dad696f19f721d526

doc/source/zuulv3.rst

@@ -560,11 +560,11 @@ OpenStack projects with custom tox environments should base them on
 
 .. code-block:: yaml
 
-    - job:
-        name: tooz-tox-py35-etcd3
-        parent: openstack-tox
-        vars:
-          tox_envlist: py35-etcd3
+    - job:
+        name: tooz-tox-py35-etcd3
+        parent: openstack-tox
+        vars:
+          tox_envlist: py35-etcd3
 
 Installation of 'sibling' requirements
 --------------------------------------

tox.ini

@@ -13,5 +13,4 @@ deps = -r{toxinidir}/requirements.txt
 commands = {posargs}
 
 [testenv:docs]
-basepython = python2
 commands = sphinx-build -W -d doc/build/doctrees -b html doc/source/ doc/build/html