YP 3.1 Docs: Updated Manual revision tables.

Scrubbed so subsequent releases are relevant to the
initial release only.

(From yocto-docs rev: 7bb2c4f851aa968eb05b11c5471b81962f268eba)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/dev-manual/dev-manual.xml

@@ -33,7 +33,7 @@
         <revhistory>
             <revision>
                 <revnumber>1.1</revnumber>
-                <date>6 October 2011</date>
+                <date>October 2011</date>
                 <revremark>The initial document released with the Yocto Project 1.1 Release.</revremark>
             </revision>
             <revision>
@@ -56,11 +56,6 @@
                 <date>October 2013</date>
                 <revremark>Released with the Yocto Project 1.5 Release.</revremark>
             </revision>
-            <revision>
-                <revnumber>1.5.1</revnumber>
-                <date>January 2014</date>
-                <revremark>Released with the Yocto Project 1.5.1 Release.</revremark>
-            </revision>
             <revision>
                 <revnumber>1.6</revnumber>
                 <date>April 2014</date>
@@ -118,7 +113,7 @@
             </revision>
             <revision>
                 <revnumber>3.0</revnumber>
-                <date>October</date>
+                <date>October 2019</date>
                 <revremark>Released with the Yocto Project 3.0 Release.</revremark>
             </revision>
             <revision>