Clarify even further that the lambda-to-block-pointer conversion is only available in Objective-C++

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@152511 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LanguageExtensions.html b/docs/LanguageExtensions.html
index b5d5773..997d184 100644
--- a/docs/LanguageExtensions.html
+++ b/docs/LanguageExtensions.html
@@ -1078,6 +1078,10 @@
 written at that point in the program, which avoids the overhead of
 copying a block to the heap in the common case.</p>
 
+<p>The conversion from a lambda to a block pointer is only available
+in Objective-C++, and not in C++ with blocks, due to its use of
+Objective-C memory management (autorelease).</p>
+
 <!-- ======================================================================= -->
 <h2 id="overloading-in-c">Function Overloading in C</h2>
 <!-- ======================================================================= -->