bug 1523962: marionette, geckodriver: fix published docs location; r=ahal

Sphinx creates an additional directory level unless the entry starts
with "/".  By using the aboslute path we can define where we want
the documentation to end up.

This causes the geckodriver and Marionette documentation to move from:

	/testing/marionette/marionette
	/testing/geckodriver/geckodriver

to:

	/testing/marionette
	/testing/geckodriver

Depends on D18088

Differential Revision: https://phabricator.services.mozilla.com/D18089

--HG--
extra : moz-landing-system : lando

testing/geckodriver/moz.build

@@ -20,7 +20,7 @@ RUST_TESTS = [
 with Files("**"):
     BUG_COMPONENT = ("Testing", "geckodriver")
 
-SPHINX_TREES["geckodriver"] = "doc"
+SPHINX_TREES["/testing/geckodriver"] = "doc"
 
-with Files('doc/**'):
-    SCHEDULES.exclusive = ['docs']
+with Files("doc/**"):
+    SCHEDULES.exclusive = ["docs"]

testing/marionette/moz.build

@@ -16,7 +16,7 @@ with Files("**"):
 with Files("harness/**"):
     SCHEDULES.exclusive = ["marionette", "firefox-ui"]
 
-SPHINX_TREES["marionette"] = "doc"
+SPHINX_TREES["/testing/marionette"] = "doc"
 SPHINX_PYTHON_PACKAGE_DIRS += ["client/marionette_driver"]
 
 with Files("doc/**"):