Document that a minor feature was added in 2.2.2. ;-(

Closes SF bug #639170.

Doc/lib/libstdtypes.tex

@@ -631,6 +631,7 @@ Return a copy of the string with leading characters removed.  If
 removed.  If given and not \code{None}, \var{chars} must be a string;
 the characters in the string will be stripped from the beginning of
 the string this method is called on.
+\versionchanged[Support for the \var{chars} argument]{2.2.2}
 \end{methoddesc}
 
 \begin{methoddesc}[string]{replace}{old, new\optional{, maxsplit}}
@@ -664,6 +665,7 @@ Return a copy of the string with trailing characters removed.  If
 removed.  If given and not \code{None}, \var{chars} must be a string;
 the characters in the string will be stripped from the end of the
 string this method is called on.
+\versionchanged[Support for the \var{chars} argument]{2.2.2}
 \end{methoddesc}
 
 \begin{methoddesc}[string]{split}{\optional{sep \optional{,maxsplit}}}
@@ -693,6 +695,7 @@ removed.  If \var{chars} is omitted or \code{None}, whitespace
 characters are removed.  If given and not \code{None}, \var{chars}
 must be a string; the characters in the string will be stripped from
 the both ends of the string this method is called on.
+\versionchanged[Support for the \var{chars} argument]{2.2.2}
 \end{methoddesc}
 
 \begin{methoddesc}[string]{swapcase}{}