corrected MakeLower/Upper() return value

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@20780 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/wxstring.tex

@@ -766,15 +766,15 @@ Same as MakeLower.
 
 \membersection{wxString::MakeLower}\label{wxstringmakelower}
 
-\func{void}{MakeLower}{\void}
+\func{wxString\&}{MakeLower}{\void}
 
-Converts all characters to lower case.
+Converts all characters to lower case and returns the result.
 
 \membersection{wxString::MakeUpper}\label{wxstringmakeupper}
 
-\func{void}{MakeUpper}{\void}
+\func{wxString\&}{MakeUpper}{\void}
 
-Converts all characters to upper case.
+Converts all characters to upper case and returns the result.
 
 \membersection{wxString::Matches}\label{wxstringmatches}