Update docs version and clear release notes for 7.0.0

llvm-svn: 321728
diff --git a/clang/docs/conf.py b/clang/docs/conf.py
index a12f99a..b38c93a 100644
--- a/clang/docs/conf.py
+++ b/clang/docs/conf.py
@@ -49,9 +49,9 @@
 # built documents.
 #
 # The short version.
-version = '6'
+version = '7'
 # The full version, including alpha/beta/rc tags.
-release = '6'
+release = '7'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.