doc: cleanup editor page

Fix some UI issues introduced with CL50952:
- increase header colspan to account for additional column
- remove ':' character from footnotes

Change-Id: I56f59b8e4b2852612b3c6c7c0dfe99125dd8b57b
Reviewed-on: https://go-review.googlesource.com/51113Reviewed-by: Jaana Burcu Dogan <jbd@google.com>

doc/editors.html

@@ -24,7 +24,7 @@ editing, navigation, testing, and debugging experience.
 an extension for Visual Studio Code to provide support for the Go programming language</li>
 <li><a href="https://www.jetbrains.com/go">Gogland</a>: Gogland is distributed either as a standalone IDE
 or as a plugin for the IntelliJ Platform IDEs</li>
-<li><a href="https://atom.io/packages/go-plus">Go-Plus</a>: Go-Plus is an Atom package that provides enhanced Go support<li>
+<li><a href="https://atom.io/packages/go-plus">Go-Plus</a>: Go-Plus is an Atom package that provides enhanced Go support</li>
 </ul>
 
 <p>
@@ -48,7 +48,7 @@ The following feature matrix lists and compares the most significant features.
     <th><img title="Go-Plus" src="/doc/editors/go-plus.png"><br>Go-Plus</th>
   </tr>
   <tr>
-    <td class="feature-row" colspan="4">Editing features</td>
+    <td class="feature-row" colspan="5">Editing features</td>
   </tr>
   <tr>
     <td>Build and run from the editor/IDE</td>
@@ -100,7 +100,7 @@ The following feature matrix lists and compares the most significant features.
     <td class="yes">Yes</td>
   </tr>
   <tr>
-    <td class="feature-row" colspan="4">Navigation features</td>
+    <td class="feature-row" colspan="5">Navigation features</td>
   </tr>
   <tr>
     <td>Display documentation inline, or open godoc in browser</td>
@@ -138,7 +138,7 @@ The following feature matrix lists and compares the most significant features.
     <td class="yes">Yes</td>
   </tr>
   <tr>
-    <td class="feature-row" colspan="4">Testing and debugging features</td>
+    <td class="feature-row" colspan="5">Testing and debugging features</td>
   </tr>
   <tr>
     <td>Debugger support</td>
@@ -186,11 +186,11 @@ The following feature matrix lists and compares the most significant features.
 </table>
 
 <p>
-<sup>1</sup>: Possible when enabled via Settings &gt; Go &gt; On Save, <code>go</code> <code>vet</code> and <code>golint</code> are available via plugins. Also runs tests on save if configured.
+<sup>1</sup>Possible when enabled via Settings &gt; Go &gt; On Save, <code>go</code> <code>vet</code> and <code>golint</code> are available via plugins. Also runs tests on save if configured.
 <br>
-<sup>2</sup>: Additionally, user input can disambiguate when two or more options are available.
+<sup>2</sup>Additionally, user input can disambiguate when two or more options are available.
 <br>
-<sup>3</sup>: Available if the <a href="https://atom.io/packages/go-debug">go-debug</a> package is installed.
+<sup>3</sup>Available if the <a href="https://atom.io/packages/go-debug">go-debug</a> package is installed.
 </p>
 
 </div>
@@ -228,4 +228,4 @@ The following feature matrix lists and compares the most significant features.
   background-color: #ebebeb;
   font-weight: bold;
 }
-</style>
\ No newline at end of file
+</style>