chore: add deprecation notice to config.commands

Add an example in help that demonstrates setting up the same
in an `on_attach` function

doc/lspconfig.txt

@@ -286,6 +286,31 @@ Example:
 >
     configs.texlab.buf_build = buf_build
 <
+
+Warning: Commands is deprecated and will be removed in future releases.
+It is recommended to use `vim.api.nvim_create_user_command()` instead in an `on_attach` function.
+
+Example:
+>
+  local function organize_imports()
+    local params = {
+      command = 'pyright.organizeimports',
+      arguments = { vim.uri_from_bufnr(0) },
+    }
+    vim.lsp.buf.execute_command(params)
+  end
+
+  local on_attach = function(client, bufnr)
+    if client.name == "pyright" then
+      vim.api.nvim_create_user_command("PyrightOrganizeImports", organize_imports, {desc = 'Organize Imports'})
+    end
+  end
+
+  require("lspconfig")['pyright'].setup({
+    on_attach = on_attach
+  })
+<
+
 ==============================================================================
 ADDING NEW SERVERS                                    *lspconfig-new*
 

lua/lspconfig/configs.lua

@@ -40,6 +40,7 @@ function configs.__newindex(t, config_name, config_def)
       commands = { config.commands, 't', true },
     }
     if config.commands then
+      vim.deprecate('lspconfig.[server].setup.commands', 'vim.api.nvim_create_user_command', '0.9', 'nvim-lspconfig')
       for _, v in pairs(config.commands) do
         validate {
           name = { v.name, 's' },