Bump the trunk version to 10.0.0svn

and clear the release notes.

llvm-svn: 366427
diff --git a/clang/docs/conf.py b/clang/docs/conf.py
index dab7026..e16ff49 100644
--- a/clang/docs/conf.py
+++ b/clang/docs/conf.py
@@ -50,9 +50,9 @@
 # built documents.
 #
 # The short version.
-version = '9'
+version = '10'
 # The full version, including alpha/beta/rc tags.
-release = '9'
+release = '10'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.