[analyzer] Rename generateNode -> addTransition in CheckerContext

Also document addTransition methods.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143059 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp b/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
index ab9631d..eeda734 100644
--- a/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
@@ -184,7 +184,7 @@
   }
 
   // From this point forward, we know that the location is not null.
-  C.generateNode(notNullState);
+  C.addTransition(notNullState);
 }
 
 void ento::registerDereferenceChecker(CheckerManager &mgr) {