Fix doc build in test script

There is some additional setup required for the docs to be built.
We need to have an implementation so there is something to add to
the api docs, and openstackdocstheme requires a git commit so it
can get the last modified timestamp. Also, we no longer generate a
Changelog since we aren't using pbr now so we need to remove that
or we have a missing file.

Change-Id: Ic79aa0fb8f7e5813bec420c8b2690b0e9ef79cc2

oslo.{{cookiecutter.module_name}}/doc/source/history.rst

@@ -1 +0,0 @@
-.. include:: ../../ChangeLog

oslo.{{cookiecutter.module_name}}/doc/source/index.rst

@@ -14,7 +14,6 @@ Contents
    reference/index
    usage
    contributing
-   history
 
 Indices and tables
 ==================

tools/test_tox_targets.sh

@@ -17,5 +17,15 @@ cd $project_dir
 
 # PBR requires a git repo for versioning
 git init .
+# openstackdocstheme requires commits for last modified calculation
+git add .
+git commit -m "Test commit"
+
+# Create an "implementation" so we have an API to document
+cat > $project_dir/oslo_testing/test.py << EOF
+def test_api():
+    """A docstring"""
+    pass
+EOF
 
 tox -e pep8,py27,py36,py37,docs,lower-constraints,cover