docs: update calendar, add news item and link release notes for 17.2.3

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

docs/index.html

@@ -16,6 +16,12 @@
 
 <h1>News</h1>
 
+<h2>October 19, 2017</h2>
+<p>
+<a href="relnotes/17.2.3.html">Mesa 17.2.3</a> is released.
+This is a bug-fix release.
+</p>
+
 <h2>October 2, 2017</h2>
 <p>
 <a href="relnotes/17.2.2.html">Mesa 17.2.2</a> is released.

docs/release-calendar.html

@@ -39,13 +39,7 @@ if you'd like to nominate a patch in the next stable release.
 <th>Notes</th>
 </tr>
 <tr>
-<td rowspan="5">17.2</td>
-<td>2017-10-13</td>
-<td>17.2.3</td>
-<td>Emil Velikov</td>
-<td></td>
-</tr>
-<tr>
+<td rowspan="4">17.2</td>
 <td>2017-10-27</td>
 <td>17.2.4</td>
 <td>Andres Gomez</td>

docs/relnotes.html

@@ -21,6 +21,7 @@ The release notes summarize what's new or changed in each Mesa release.
 </p>
 
 <ul>
+<li><a href="relnotes/17.2.3.html">17.2.3 release notes</a>
 <li><a href="relnotes/17.2.2.html">17.2.2 release notes</a>
 <li><a href="relnotes/17.1.10.html">17.1.10 release notes</a>
 <li><a href="relnotes/17.2.1.html">17.2.1 release notes</a>