C#: fix some ql/non-doc-block warnings

Author: erik-krogh

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -431,7 +431,7 @@ class SsaPhiNode extends Node, TSsaPhiNode {
 
   SsaPhiNode() { this = TSsaPhiNode(phi) }
 
-  /* Get the phi node associated with this node. */
+  /** Gets the phi node associated with this node. */
   Ssa::PhiNode getPhiNode() { result = phi }
 
   override Declaration getEnclosingCallable() { result = this.getFunction() }

csharp/ql/lib/semmle/code/csharp/exprs/Creation.qll

@@ -435,10 +435,10 @@ class AnonymousFunctionExpr extends Expr, Callable, Modifiable, @anonymous_funct
  * A lambda expression, for example `(int x) => x + 1`.
  */
 class LambdaExpr extends AnonymousFunctionExpr, @lambda_expr {
-  /* Holds if this lambda expression has explicit return type. */
+  /** Holds if this lambda expression has explicit return type. */
   predicate hasExplicitReturnType() { lambda_expr_return_type(this, _) }
 
-  /* Gets the explicit return type of this lambda expression, if any. */
+  /** Gets the explicit return type of this lambda expression, if any. */
   Type getExplicitReturnType() { lambda_expr_return_type(this, getTypeRef(result)) }
 
   override string toString() { result = "(...) => ..." }