Nominate Sirraide for AST visitors and Sema (llvm#114092)

Sirraide has been actively reviewing Sema code for a while now and
definitely has the expertise to help maintain that section of the
compiler. Further, he has been refactoring AST visitors to try to reduce
the compile time overhead associated with them and would be a good
resource for keeping an eye on that part of the code base too.

Author: AaronBallman

clang/Maintainers.rst

@@ -33,6 +33,12 @@ AST matchers
 | aaron\@aaronballman.com (email), aaron.ballman (Phabricator), AaronBallman (GitHub), AaronBallman (Discourse), aaronballman (Discord), AaronBallman (IRC)
 
 
+AST Visitors
+~~~~~~~~~~~~
+| Sirraide
+| aeternalmail\@gmail.com (email), Sirraide (GitHub), Ætérnal (Discord), Sirraide (Discourse)
+
+
 Clang LLVM IR generation
 ~~~~~~~~~~~~~~~~~~~~~~~~
 | John McCall
@@ -57,6 +63,12 @@ Analysis & CFG
 | sgatev\@google.com (email), sgatev (Phabricator), sgatev (GitHub)
 
 
+Sema
+~~~~
+| Sirraide
+| aeternalmail\@gmail.com (email), Sirraide (GitHub), Ætérnal (Discord), Sirraide (Discourse)
+
+
 Experimental new constant interpreter
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 | Timm Bäder