Rename -dependency-graphviz to -dependencncy-dot

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149645 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/DependencyGraph.cpp b/lib/Frontend/DependencyGraph.cpp
index 6d4825f..eebaf0c 100644
--- a/lib/Frontend/DependencyGraph.cpp
+++ b/lib/Frontend/DependencyGraph.cpp
@@ -7,7 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This code generates a header dependency graph in GraphViz format.
+// This code generates a header dependency graph in DOT format, for use
+// with, e.g., GraphViz.
 //
 //===----------------------------------------------------------------------===//