v.patch: update manual

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@73635 15284696-431f-4ddb-bdfa-cd5b030d7da7

vector/v.patch/v.patch.html

@@ -12,16 +12,25 @@ patched together (e.g., border lines) will have to be
 edited or removed after <em>v.patch</em> is run. Such
 editing can be done automatically using
 <em><a href="v.clean.html">v.clean</a></em>.
-<p>Lines may need to be
-snapped with <em><a href="v.clean.html">v.clean</a>
-tool=snap,break,rmdupl</em>.
-<p>Boundaries may need to be cleaned with
+<p>
+Lines may need to be snapped with <em><a 
+href="v.clean.html">v.clean</a> tool=snap,break,rmdupl</em>.
+<p>
+Boundaries may need to be cleaned with
 <em><a href="v.clean.html">v.clean</a> tool=break,rmdupl,rmsa</em>
 repeatedly until the <em>rmsa</em> tool (Remove small angles at nodes)
 no longer modifies any boundaries. If vector topology is still not
 clean, boundaries may also need to be snapped with
 <em><a href="v.clean.html">v.clean</a> tool=snap,break,rmdupl</em>.
-<p>When using the <em>-a</em> flag, the user has to make sure that the
+<p>
+When using the <em>-e</em> flag, <em>v.patch</em> shifts category (cat) 
+values in the output so that category numbers from the different input 
+maps do not overlap. This shift is applied to both the category values 
+of the features and the category values in the attribute tables. Hence, 
+there is no need to run <em><a href="v.category.html">v.category</a></em> 
+and <em><a href="v.db.update.html">v.db.update</a></em> beforehand.
+<p>
+When using the <em>-a</em> flag, the user has to make sure that the
 features in the different maps added to the output map do not have
 overlapping category numbers, unless identical category numbers
 reflect identical attributes, otherwise the attributes of the added