Merge pull request #69569 from al45tair/update-codeowners-2023-11-01

Author: shahmishal

.github/CODEOWNERS

@@ -148,8 +148,10 @@
 /stdlib/public/Cxx/                       @zoecarver @hyp @egorzhdan
 /stdlib/public/Distributed/               @ktoso
 /stdlib/public/Observation/               @phausler
+/stdlib/public/Threading/                 @al45tair
 /stdlib/public/Windows/                   @compnerd
 /stdlib/public/libexec/swift-backtrace/   @al45tair
+/stdlib/public/runtime/                   @mikeash @al45tair
 
 # test
 /test/ASTGen/                                       @zoecarver @CodaFi