Give correct length of string.

Doc/lib/libmd5.tex

@@ -53,7 +53,7 @@ arguments, i.e.\ \code{m.update(a); m.update(b)} is equivalent to
 
 \begin{funcdesc}{digest}{}
 Return the digest of the strings passed to the \code{update()}
-method so far.  This is an 8-byte string which may contain
+method so far.  This is an 16-byte string which may contain
 non-\ASCII{} characters, including null bytes.
 \end{funcdesc}
 

Doc/libmd5.tex

@@ -53,7 +53,7 @@ arguments, i.e.\ \code{m.update(a); m.update(b)} is equivalent to
 
 \begin{funcdesc}{digest}{}
 Return the digest of the strings passed to the \code{update()}
-method so far.  This is an 8-byte string which may contain
+method so far.  This is an 16-byte string which may contain
 non-\ASCII{} characters, including null bytes.
 \end{funcdesc}