doc: put text into header of 1st column in table to generate page correctly

>From the table without header text of 1st column, docutils generates
the table with fully empty header row.

mercurial/commands.py

@@ -4769,14 +4769,14 b' def remove(ui, repo, *pats, **opts):'
       (as reported by :hg:`status`). The actions are Warn, Remove
       (from branch) and Delete (from disk):
 
-      ======= == == == ==
-              A  C  M  !
-      ======= == == == ==
-      none    W  RD W  R
-      -f      R  RD RD R
-      -A      W  W  W  R
-      -Af     R  R  R  R
-      ======= == == == ==
+      ========= == == == ==
+      opt/state A  C  M  !
+      ========= == == == ==
+      none      W  RD W  R
+      -f        R  RD RD R
+      -A        W  W  W  R
+      -Af       R  R  R  R
+      ========= == == == ==
 
       Note that remove never deletes files in Added [A] state from the
       working directory, not even if option --force is specified.

tests/test-help.t

@@ -1691,7 +1691,7 b' Dish up an empty repo; serve it cold.'
   (from branch) and Delete (from disk):
   </p>
   <table>
-  <tr><td></td>
+  <tr><td>opt/state</td>
   <td>A</td>
   <td>C</td>
   <td>M</td>