feat: add default = true for highlight groups definition.

1. Add `default = true` for highlight groups, allow user to custom style.
2. Add descriptions for highlight groups in doc `rest-nvim.txt`

Author: xieyonn

doc/rest-nvim.txt

@@ -12,6 +12,7 @@ rest.nvim ···································
 rest.nvim user commands ··································· |rest-nvim.commands|
 rest.nvim user events ······································· |rest-nvim.events|
 rest.nvim configuration ····································· |rest-nvim.config|
+rest.nvim highlight groups ························ |rest-nvim.highlight-groups|
 
 rest.setup({user_configs?})                                         *rest.setup*
     @deprecated use `vim.g.rest_nvim` instead
@@ -247,4 +248,14 @@ rest.Opts.Highlight                                        *rest.Opts.Highlight*
         {timeout?}  (number)    Duration time of the request highlighting in milliseconds (Default: `750`)
 
 
+==============================================================================
+rest.nvim highlight groups                          *rest-nvim.highlight-groups*
+
+
+  Highlight Group      Default                          Description
+  -------------------- -------------------------------- --------------------
+  RestText             Comment                          winbar text
+  RestPaneTitleNC      Statement                        winbar text in non-current pane
+  RestPaneTitle        Statement + bold + underline     winbar Text in current pane
+
 vim:tw=78:ts=8:noet:ft=help:norl:

lua/rest-nvim/ui/result.lua

@@ -233,12 +233,13 @@ local function get_hl_group_fg(name)
     return string.format("#%06X", vim.api.nvim_get_hl(0, { name = name, link = false }).fg)
 end
 
-vim.api.nvim_set_hl(0, "RestText", { fg = get_hl_group_fg("Comment") })
-vim.api.nvim_set_hl(0, "RestPaneTitleNC", { fg = get_hl_group_fg("Statement") })
+vim.api.nvim_set_hl(0, "RestText", { fg = get_hl_group_fg("Comment"), default = true })
+vim.api.nvim_set_hl(0, "RestPaneTitleNC", { fg = get_hl_group_fg("Statement"), default = true })
 vim.api.nvim_set_hl(0, "RestPaneTitle", {
     fg = get_hl_group_fg("Statement"),
     bold = true,
     underline = true,
+    default = true,
 })
 
 ---Check if UI window is shown in current tabpage