manual: change hardcoded container size (https://trac.osgeo.org/grass/changeset/62109 and previous) to percentage

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@62118 15284696-431f-4ddb-bdfa-cd5b030d7da7

man/grassdocs.css

@@ -22,7 +22,8 @@ body{
     margin: 0 auto;
     padding-left:  10px;
     padding-right: 10px;
-    width: 750px;
+#    width: 750px;
+    width: 70%;
     background-color: white;
     height:auto !important;
     min-height: 100%;