Grammar fix

Doc/lib/libpdb.tex

@@ -178,12 +178,12 @@ most commands.
 \item[d(own)]
 
 Move the current frame one level down in the stack trace
-(to an newer frame).
+(to a newer frame).
 
 \item[u(p)]
 
 Move the current frame one level up in the stack trace
-(to a older frame).
+(to an older frame).
 
 \item[b(reak) \optional{\optional{\var{filename}:}\var{lineno}\code{\Large{|}}\var{function}\optional{, \var{condition}}}]