add graph command in git tuto

add number increase command in vim tuto

tutos/vim.txt

@@ -138,6 +138,12 @@
 **=G** rétablit la bonne indentation pour toute la page
 **''** go to last cursor position
 **gx** open the file under cursor, or url or links
+**g ctrl a** increment a column of numbers :
+	- create a column of "0"
+	- then select them in visual block **ctrl v arrow**
+	- then hit **g ctrl a**
+	- or **g ctrl a a** if using screen
+	- **ctrl a** is a vim feature to increase a number
 
 /REMPLACER/
 **:s/old/new** remplace la 1ere occurence de ancien par nouveau