Slightly expand on the instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20121 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CFEBuildInstrs.html b/docs/CFEBuildInstrs.html
index 86d2396..eb7a318 100644
--- a/docs/CFEBuildInstrs.html
+++ b/docs/CFEBuildInstrs.html
@@ -126,7 +126,9 @@
  % set path = ( `cd llvm/Debug/bin && pwd` $path )
 </pre></li>
 
-<li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
+<li><p>Unpack the C/C++ front-end source into cfrontend/src, either by
+       untar'ing an llvm-gcc.tar.gz file or checking out CVS into this
+       directory.</p></li>
 
 <li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
 <pre>