chore: revert filetype separator to '/'

Author: zdm

doc/vsnip.txt

@@ -76,9 +76,9 @@ VARIABLE                                                      *vsnip-variable*
     languages like this:
 
 >
-    let g:vsnip_filetypes['vim.lua'] = ['lua', 'vim/lua']
+    let g:vsnip_filetypes['vim/lua'] = ['lua', 'vim/lua']
     let g:vsnip_filetypes['vue'] = ['html']
-    let g:vsnip_filetypes['vim.javascript'] = ['javascript', 'vue/javascript']
+    let g:vsnip_filetypes['vim/javascript'] = ['javascript', 'vue/javascript']
 <
 
  let g:vsnip_deactivate_on = g:vsnip#DeactivateOn.OutsideOfSnippet~

lua/vsnip/treesitter.lua

@@ -48,7 +48,7 @@ function M.get_ft_at_cursor ( bufnr )
           local parent_filetype = get_parser_filetype( parent_language )
 
           if parent_filetype ~= "" then
-            filetypes.injected_filetype = parent_filetype .. "." .. filetype
+            filetypes.injected_filetype = parent_filetype .. "/" .. filetype
           end
         end