docs: plugins.txt #35680

Co-authored-by: Justin M. Keyes <justinkz@gmail.com>

src/gen/gen_vimdoc.lua

@@ -184,11 +184,9 @@ local config = {
       'version.lua',
 
       -- Sections at the end, in a specific order:
-      'tohtml.lua',
       '_extui.lua',
     },
     files = {
-      'runtime/lua/tohtml.lua',
       'runtime/lua/vim/_editor.lua',
       'runtime/lua/vim/_extui.lua',
       'runtime/lua/vim/_inspector.lua',
@@ -249,9 +247,6 @@ local config = {
       elseif name == 'builtin' then
         return 'VIM'
       end
-      if name == 'tohtml' then
-        return 'Lua module: tohtml'
-      end
       return 'Lua module: vim.' .. name
     end,
     helptag_fmt = function(name)
@@ -261,8 +256,6 @@ local config = {
         return 'lua-vim-system'
       elseif name == '_options' then
         return 'lua-vimscript'
-      elseif name == 'tohtml' then
-        return 'tohtml'
       end
       return 'vim.' .. name:lower()
     end,
@@ -436,6 +429,21 @@ local config = {
       return { 'vim.pack' }
     end,
   },
+  plugins = {
+    filename = 'plugins.txt',
+    section_order = {
+      'tohtml.lua',
+    },
+    files = {
+      'runtime/lua/tohtml.lua',
+    },
+    section_fmt = function(name)
+      return 'Builtin plugin: ' .. name:lower()
+    end,
+    helptag_fmt = function(name)
+      return name:lower()
+    end,
+  },
 }
 
 --- @param ty string