Update v.reclass.html: either 'rules' or 'column' option must be spec…

…ified (OSGeo#3067)

Add a note about the fact that either 'rules' or 'column' option must be specified

vector/v.reclass/v.reclass.html

@@ -27,6 +27,8 @@ <h2>NOTES</h2>
 <p>For dissolving common boundaries, see
 <em><a href="v.dissolve.html">v.dissolve</a></em>.
 
+<p>Either the <b>rules</b> or <b>column</b> option must be specified.
+
 <h2>EXAMPLES</h2>
 
 <h3>Example 1: Reclass by rules</h3>
@@ -35,7 +37,7 @@ <h3>Example 1: Reclass by rules</h3>
 v.reclass input=land output=land_u type=boundary rules=land.rcl
 </pre></div>
 
-the rules file contains :
+The rules file contains:
 
 <div class="code"><pre>
 # land reclass file
@@ -71,7 +73,7 @@ <h3>Example 2: Reclass by attribute column</h3>
 
 <h2>KNOWN ISSUES</h2>
 
-No table is created for reclassed layer if <b>rules</b> option is used.
+No table is created for reclassed layer if the <b>rules</b> option is used.
 
 <h2>SEE ALSO</h2>