changing rtd title

Signed-off-by: Alex McCaskey <mccaskeyaj@ornl.gov>

docs/source/index.rst

@@ -3,8 +3,8 @@
    You can adapt this file completely to your liking, but it should at least
    contain the root `toctree` directive.
 
-Welcome to XACC's documentation!
-================================
+XACC Documentation
+==================
 
 .. image:: ../assets/xacc-readme.jpg