v.buffer: add one more example

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@69058 15284696-431f-4ddb-bdfa-cd5b030d7da7

vector/v.buffer/v.buffer.html

@@ -123,6 +123,21 @@ Buffer of 100m around the "lakes" polygons (map subset, original areas
 shown in black)
 </center>
 
+<h3>Buffer inside input areas</h3>
+
+<div class="code"><pre>
+v.buffer input=lakes output=lakes_buffer type=area distance=-50
+</pre></div>
+
+<center>
+<img src="v_buffer_areas_int.png" border="1"><br>
+Internal buffer of 50m inside the "lakes" polygons (map subset, original areas
+shown in black) <br>
+Not all features are buffered, only the polygons that allow to create inside
+a topological cleaned polygon.
+</center>
+
+
 <h2>REFERENCES</h2>
 
 <ul>