Tweak comment based on Daniel's recently added '-emit-ast' option.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80684 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang-c/Index.h b/include/clang-c/Index.h
index 1b9ba4c..9199803 100644
--- a/include/clang-c/Index.h
+++ b/include/clang-c/Index.h
@@ -22,14 +22,10 @@
 
 /*
    Clang indeX abstractions. The backing store for the following API's will be 
-   clangs PCH file (which contains AST's, or Abstract Syntax Trees). PCH files
-   are created by the following command:
+   clangs AST file (currently based on PCH). AST files are created as follows:
    
-   "clang -S -Xclang -emit-pch <sourcefile.langsuffix> -o <sourcefile.ast>". 
+   "clang -emit-ast <sourcefile.langsuffix> -o <sourcefile.ast>". 
    
-   If the ast file format ends up diverging from the pch file format, we will 
-   need to add a new switch (-emit-ast). For now, the contents are identical.
-
    Naming Conventions: To avoid namespace pollution, data types are prefixed 
    with "CX" and functions are prefixed with "clang_".
 */