Documentation: add a missing space

llvm-svn: 170542
diff --git a/llvm/docs/design_and_overview.rst b/llvm/docs/design_and_overview.rst
index 22e8125..4b1d627 100644
--- a/llvm/docs/design_and_overview.rst
+++ b/llvm/docs/design_and_overview.rst
@@ -21,7 +21,7 @@
 
   Book chapter providing a compiler hacker's introduction to LLVM.
 
-* `LLVM: A Compilation Framework forLifelong Program Analysis & Transformation
+* `LLVM: A Compilation Framework for Lifelong Program Analysis & Transformation
   <http://llvm.org/pubs/2004-01-30-CGO-LLVM.html>`_
 
   Design overview.