Editorial: Fix wrong type of Time Record [[Days]] field

This field is not ≥ 0, as can be trivially verified by calling AddTime
with any Time Record and a time duration < -86400,000,000,000.

Credit to Vebjørn Øiestad and Aria Bjørnbakken Eide for discovering
this.

Co-Authored-By: Vebjørn Øiestad <[email protected]>
Co-Authored-By: Aria Bjørnbakken Eide <[email protected]>

Author: 3 people

spec/plaintime.html

@@ -409,7 +409,7 @@ <h1>Time Records</h1>
           </tr>
           <tr>
             <td>[[Days]]</td>
-            <td>an integer ≥ 0</td>
+            <td>an integer</td>
             <td>A number of overflow days.</td>
           </tr>
           <tr>
@@ -455,7 +455,7 @@ <h1>
           _millisecond_: an integer in the inclusive interval from 0 to 999,
           _microsecond_: an integer in the inclusive interval from 0 to 999,
           _nanosecond_: an integer in the inclusive interval from 0 to 999,
-          optional _deltaDays_: a non-negative integer,
+          optional _deltaDays_: an integer,
         ): a Time Record
       </h1>
       <dl class="header">