Rename AdvancedGuide.md to advanced.md and adjust the links.

Part of documentation rationalization work

googlemock/docs/CheatSheet.md

@@ -229,7 +229,7 @@ The `argument` can be either a C string or a C++ string object:
 
 `ContainsRegex()` and `MatchesRegex()` use the regular expression
 syntax defined
-[here](../../googletest/docs/AdvancedGuide.md#regular-expression-syntax).
+[here](../../googletest/docs/advanced.md#regular-expression-syntax).
 `StrCaseEq()`, `StrCaseNe()`, `StrEq()`, and `StrNe()` work for wide
 strings as well.
 

googlemock/docs/CookBook.md

@@ -3655,6 +3655,6 @@ This printer knows how to print built-in C++ types, native arrays, STL
 containers, and any type that supports the `<<` operator.  For other
 types, it prints the raw bytes in the value and hopes that you the
 user can figure it out.
-[Google Test's advanced guide](../../googletest/docs/AdvancedGuide.md#teaching-google-test-how-to-print-your-values)
+[Google Test's advanced guide](../../googletest/docs/advanced.md#teaching-google-test-how-to-print-your-values)
 explains how to extend the printer to do a better job at
 printing your particular type than to dump the bytes.

googlemock/docs/ForDummies.md

@@ -187,7 +187,7 @@ sometimes causes the test program to crash.  You'll still be able to
 notice that the test has failed, but it's not a graceful failure.
 
 A better solution is to use Google Test's
-[event listener API](../../googletest/docs/AdvancedGuide.md#extending-google-test-by-handling-test-events)
+[event listener API](../../googletest/docs/advanced.md#extending-google-test-by-handling-test-events)
 to report a test failure to your testing framework properly.  You'll need to
 implement the `OnTestPartResult()` method of the event listener interface, but it
 should be straightforward.