Improve documentation.

llvm-svn: 50768
diff --git a/llvm/include/llvm-c/BitWriter.h b/llvm/include/llvm-c/BitWriter.h
index bc5699f..008ff9f 100644
--- a/llvm/include/llvm-c/BitWriter.h
+++ b/llvm/include/llvm-c/BitWriter.h
@@ -28,7 +28,8 @@
 
 /*===-- Operations on modules ---------------------------------------------===*/
 
-/* Writes a module to an open file descriptor. Returns 0 on success. */ 
+/* Writes a module to an open file descriptor. Returns 0 on success.
+   Closes the Handle. Use dup first if this is not what you want. */ 
 int LLVMWriteBitcodeToFileHandle(LLVMModuleRef M, int Handle);
 
 /* Writes a module to the specified path. Returns 0 on success. */