ADD: formatting.expandable_indicator to show the expandable indicator (#1207)

* ADD: formatting.expandable_indicator to show the `expandable` indicator

* UPDATA: doc/cmp.txt  lua/cmp/entry.lua  lua/cmp/typed/cmp.lua

lua/cmp/entry.lua

@@ -236,16 +236,17 @@ entry.get_vim_item = function(self, suggest_offset)
     local abbr = str.oneline(completion_item.label)
 
     -- ~ indicator
-    local is_snippet = false
+    local is_expandable = false
+    local expandable_indicator = config.get().formatting.expandable_indicator
     if #(misc.safe(completion_item.additionalTextEdits) or {}) > 0 then
-      is_snippet = true
+    is_expandable = true
     elseif completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
-      is_snippet = self:get_insert_text() ~= word
+    is_expandable = self:get_insert_text() ~= word
     elseif completion_item.kind == types.lsp.CompletionItemKind.Snippet then
-      is_snippet = true
+    is_expandable = true
     end
-    if is_snippet then
-      abbr = abbr .. '~'
+    if expandable_indicator and is_expandable then
+    abbr = abbr .. '~'
     end
 
     -- append delta text