feat docs: release 2.12

Tests: протестировано CI
commit_hash:19e4dbcb836c8d0241a42da8ffa41a2688d69c65

Author: apolukhin

cmake/GetUserverVersion.cmake

@@ -22,7 +22,7 @@ else()
 endif()
 
 set(USERVER_MAJOR_VERSION 2)
-set(USERVER_MINOR_VERSION 12-rc)
+set(USERVER_MINOR_VERSION 12)
 
 set(USERVER_VERSION "${USERVER_MAJOR_VERSION}.${USERVER_MINOR_VERSION}")
 string(REPLACE "-" "_" USERVER_VERSION_STR "${USERVER_VERSION}")