fix(build): vimdoc tags are not validated #32801

Problem:
"make lintdoc" is not validating vimdoc (:help) tags.

Solution:
- Call `lang_tree:parse()` to init the parser.
- Load netrw 🤢 explicitly, since it was moved to `pack/dist/opt/`.
- Fix invalid help tags.

src/gen/gen_help_html.lua

@@ -778,6 +778,7 @@ local function parse_buf(fname, text, parser_path)
     vim.treesitter.language.add('vimdoc', { path = parser_path })
   end
   local lang_tree = assert(vim.treesitter.get_parser(buf, nil, { error = false }))
+  lang_tree:parse()
   return lang_tree, buf
 end
 
@@ -1397,6 +1398,9 @@ function M.validate(help_dir, include, parser_path)
   local files_to_errors = {} ---@type table<string, string[]>
   ensure_runtimepath()
   tagmap = get_helptags(vim.fs.normalize(help_dir))
+  --- XXX: Append tags from netrw, until we remove it...
+  local netrwtags = get_helptags(vim.fs.normalize('$VIMRUNTIME/pack/dist/opt/netrw/doc/'))
+  tagmap = vim.tbl_extend('keep', tagmap, netrwtags)
   helpfiles = get_helpfiles(help_dir, include)
   parser_path = parser_path and vim.fs.normalize(parser_path) or nil
 
@@ -1424,7 +1428,7 @@ function M.validate(help_dir, include, parser_path)
   }
 end
 
---- Validates vimdoc files on $VIMRUNTIME. and print human-readable error messages if fails.
+--- Validates vimdoc files in $VIMRUNTIME, and prints error messages on failure.
 ---
 --- If this fails, try these steps (in order):
 --- 1. Fix/cleanup the :help docs.
@@ -1464,7 +1468,7 @@ function M.test_gen(help_dir)
   print('doc path = ' .. vim.uv.fs_realpath(help_dir))
 
   -- Because gen() is slow (~30s), this test is limited to a few files.
-  local input = { 'help.txt', 'index.txt', 'nvim.txt' }
+  local input = { 'api.txt', 'index.txt', 'nvim.txt' }
   local rv = M.gen(help_dir, tmpdir, input)
   eq(#input, #rv.helpfiles)
   eq(0, rv.err_count, 'parse errors in :help docs')

src/nvim/options.lua

@@ -6236,7 +6236,7 @@ local options = {
         	set path=,,
         <	- A directory name may end in a ':' or '/'.
         - Environment variables are expanded |:set_env|.
-        - When using |netrw.vim| URLs can be used.  For example, adding
+        - When using |netrw| URLs can be used.  For example, adding
           "https://www.vim.org" will make ":find index.html" work.
         - Search upwards and downwards in a directory tree using "*", "**" and
           ";".  See |file-searching| for info and syntax.