r.timestamp: typo in the manual

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@70666 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.timestamp/r.timestamp.html

@@ -15,7 +15,7 @@ remove the timestamp from a raster map, use <b>date=none</b>.
 
 The timestamp values must use the format as described in the <em>GRASS
 Datetime Library</em>. The source tree for this library should have a
-description of the format. For convience, the formats are reproduced
+description of the format. For convenience, the formats are reproduced
 here:
 
 <p>There are two types of datetime values: