"Thin" version of floor division docs: add // to the list of operators

and //= to the list of other delimiter tokens.

I'll work on it again when it's not so late...

Doc/ref/ref2.tex

@@ -563,7 +563,7 @@ The following tokens are operators:
 \index{operators}
 
 \begin{verbatim}
-+       -       *       **      /       %
++       -       *       **      /       //      %
 <<      >>      &       |       ^       ~
 <       >       <=      >=      ==      !=      <>
 \end{verbatim}
@@ -581,8 +581,8 @@ The following tokens serve as delimiters in the grammar:
 \begin{verbatim}
 (       )       [       ]       {       }
 ,       :       .       `       =       ;
-+=      -=      *=      /=      %=      **=
-&=      |=      ^=      >>=     <<=
++=      -=      *=      /=      //=     %=
+&=      |=      ^=      >>=     <<=     **=
 \end{verbatim}
 
 The period can also occur in floating-point and imaginary literals.  A