Extend the doc with more examples

DOC.md

@@ -746,11 +746,24 @@ more than once). You can escape $ by repeating it.
 
 In order to use add something like this to your config:
 ```vim
-vnoremap <leader>e  "pd:lua require('luasnip.extras.otf').on_the_fly()<cr>
-nnoremap <leader>e  "p:lua require('luasnip.extras.otf').on_the_fly()<cr>
+vnoremap <c-f>  "ed:lua require('luasnip.extras.otf').on_the_fly()<cr>
+inoremap <c-f>  <C-\><C-O>"e:lua require('luasnip.extras.otf').on_the_fly()<cr>
 ```
-Notice that you can use your own mapping instead of <leader>e  and you can pick another register
-instead of `"p`
+
+Notice that you can use your own mapping instead of <c-f>  and you can pick another register
+instead of `"p`. You can even use it several times, as if it where a macro if you add several
+mapppings like:
+```vim
+; For register a
+vnoremap <c-f>a  "ad:lua require('luasnip.extras.otf').on_the_fly()<cr>
+inoremap <c-f>a  <C-\><C-O>"a:lua require('luasnip.extras.otf').on_the_fly()<cr>
+
+
+; For register b
+vnoremap <c-f>b  "bd:lua require('luasnip.extras.otf').on_the_fly()<cr>
+inoremap <c-f>b  <C-\><C-O>"b:lua require('luasnip.extras.otf').on_the_fly()<cr>
+```
+
 # LSP-SNIPPETS
 
 Luasnip is capable of parsing lsp-style snippets using