Editorial: Remove note about proposal-intl-era-monthcode

The information here is all that's needed for ECMA-262, the rest will
appear in the ECMA-402 section.

Author: ptomato

spec/calendar.html

@@ -138,12 +138,6 @@ <h1>Calendar Date Records</h1>
                 See also ISOWeekOfYear.
               </p>
               <p>The Year-Week Record contains *undefined* in [[Week]] and [[Year]] field for calendars that do not have a well-defined week calendar system.</p>
-              <emu-note type="editor">
-                <p>
-                  More details about this field will be specified in
-                  <a href="https://tc39.es/proposal-intl-era-monthcode/">the Intl era and monthCode proposal</a>.
-                </p>
-              </emu-note>
             </td>
           </tr>
           <tr>