nvim: modules: completion: min_length needs to be 2

This is required if we want completion to trigger on identifiers like
'if' to be able to select snippets.

nvim/.config/nvim/lua/modules/completion.lua

@@ -4,7 +4,7 @@ require'compe'.setup {
   enabled              = true;
   autocomplete         = true;
   debug                = false;
-  min_length           = 3;
+  min_length           = 2;
   preselect            = 'enable';
   throttle_time        = 80;
   source_timeout       = 200;