C++: Mention localExpr{Flow,Taint} in module QLDoc

Author: jbj

cpp/ql/src/semmle/code/cpp/dataflow/DataFlow.qll

@@ -11,8 +11,10 @@
  *
  * To use global (interprocedural) data flow, extend the class
  * `DataFlow::Configuration` as documented on that class. To use local
- * (intraprocedural) data flow, invoke `DataFlow::localFlow` or
- * `DataFlow::LocalFlowStep` with arguments of type `DataFlow::Node`.
+ * (intraprocedural) data flow between expressions, call
+ * `DataFlow::localExprFlow`. For more general cases of local data flow, call
+ * `DataFlow::localFlow` or `DataFlow::localFlowStep` with arguments of type
+ * `DataFlow::Node`.
  */
 import cpp
 

cpp/ql/src/semmle/code/cpp/dataflow/TaintTracking.qll

@@ -6,6 +6,13 @@
  * the information from the source is preserved at the sink. For example, taint
  * propagates from `x` to `x + 100`, but it does not propagate from `x` to `x >
  * 100` since we consider a single bit of information to be too little.
+ *
+ * To use global (interprocedural) taint tracking, extend the class
+ * `TaintTracking::Configuration` as documented on that class. To use local
+ * (intraprocedural) taint tracking between expressions, call
+ * `TaintTracking::localExprTaint`. For more general cases of local taint
+ * tracking, call `TaintTracking::localTaint` or
+ * `TaintTracking::localTaintStep` with arguments of type `DataFlow::Node`.
  */
 import semmle.code.cpp.dataflow.DataFlow
 import semmle.code.cpp.dataflow.DataFlow2