Update function header.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@5534 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Include/Library/PcdLib.h

@@ -1,7 +1,15 @@
 /** @file
-PCD Library Class Interface Declarations
+PCD Library Class provides PCD usage macro interface for all PCD types. It should be 
+included at any module who use PCD. 
 
-Copyright (c) 2006 - 2007, Intel Corporation                                                         
+If module use dynamic/dynamicex PCD, module should be linked to PEIM/DXE library 
+instance to access that PCD.
+If module uses PatchableInModule type PCD, also need library instance produce LibPatchPcdSetPtr()
+interface.
+For FeatureFlag/Fixed PCD, macro interface is translated to an variable or macro
+which is auto-generated by build tool in module's autogen.h/autogen.c
+
+Copyright (c) 2006 - 2008, Intel Corporation. <BR>                                                         
 All rights reserved. This program and the accompanying materials                          
 are licensed and made available under the terms and conditions of the BSD License         
 which accompanies this distribution.  The full text of the license may be found at        
@@ -641,8 +649,6 @@ LibPcdSetExBool (
   @param[in, out] TokenData       A pointer to the token data being set.
   @param[in]      TokenDataSize   The size, in bytes, of the data being set.
 
-  @retval VOID
-
 **/
 typedef
 VOID
@@ -667,8 +673,6 @@ VOID
   @param[in]  NotificationFunction  The function to call when the token 
                                     specified by Guid and TokenNumber is set.
 
-  @retval VOID
-
 **/
 VOID
 EFIAPI
@@ -686,8 +690,6 @@ LibPcdCallbackOnSet (
   @param[in]  TokenNumber   Specify the token number.
   @param[in]  NotificationFunction The callback function to be unregistered.
 
-  @retval VOID
-
 **/
 VOID
 EFIAPI