Update v.in.ascii.html (#60)

Added a pointer just above the example to the second reference at the bottom of the page.

vector/v.in.ascii/v.in.ascii.html

@@ -103,7 +103,7 @@ cut -d<the_field_separator_character> -f<comma-separated_list_of_column
 
 <h3>Example 1a) - standard format mode</h3>
 Sample ASCII polygon vector map for 'standard' format mode. 
-The two areas will be assigned categories 20 and 21. 
+The two areas will be assigned categories 20 and 21. For details on the structure of standard format data files see the second Reference at the bottom of this page.
 <p><div class="code"><pre>
 echo "ORGANIZATION: GRASS Development Team
 DIGIT DATE:   1/9/2005