Improve help messages for multi-day and series interim meeting types. Fixes ietf-tools#2194. Commit ready for merge.

 - Legacy-Id: 13293

Author: rpcross

ietf/templates/meeting/interim_request.html

@@ -56,15 +56,15 @@ <h1>Interim Meeting Request</h1>
     <div class="form-group meeting-type-help mth-multi" style="display: none;">
         <div class="col-md-offset-2">
             <div class="col-md-10">
-                <p class="help-block">Use Multi-Day to request one meeting with sessions over multiple days.</p>
+                <p class="help-block">Use Multi-Day for a single meeting that spans more than one contiguous workday. Do not use Multi-Day for a series of separate meetings (such as periodic interim calls). Use Series instead.</p>
             </div>
         </div>
     </div>
 
     <div class="form-group meeting-type-help mth-series" style="display: none;">
         <div class="col-md-offset-2">
             <div class="col-md-10">
-                <p class="help-block">Use Series to request a number of separate meetings.  In Person series is not supported.</p>
+                <p class="help-block">Use Series for a series of separate meetings, such as periodic interim calls. Use Multi-Day for a single meeting that spans more than one contiguous workday.</p>
             </div>
         </div>
     </div>