Use correct syntax highliter in code blocks.  Noticed by Sean Silva.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158359 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CommandGuide/opt.rst b/docs/CommandGuide/opt.rst
index 31e5716..72f1903 100644
--- a/docs/CommandGuide/opt.rst
+++ b/docs/CommandGuide/opt.rst
@@ -86,7 +86,7 @@
  of options available, use the following command:
 
 
- .. code-block:: perl
+ .. code-block:: sh
 
      llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
 
@@ -161,7 +161,7 @@
  optimizations, use the **-help** and **-load** options together. For example:
 
 
- .. code-block:: perl
+ .. code-block:: sh
 
      opt -load=plugin.so -help