docs, remove 'guifontset' #11708

- remove redundant autocmd list
  This "grouped" list is useless, it only gets in the way when searching
  for event names.
- intro.txt: cleanup
- starting.txt: update, revisit
- doc: `:help bisect`
- mbyte.txt: update aliases 1656367b90. closes #11960
- options: remove 'guifontset'. Why:
  - It is complicated and is used by almost no one.
  - It is unlikely to be implemented by Nvim GUIs (complicated to parse,
    specific to Xorg...).

runtime/lua/vim/lsp.lua

@@ -922,7 +922,7 @@ end
 --- To stop all clients:
 ---
 --- <pre>
---- vim.lsp.stop_client(lsp.get_active_clients())
+--- vim.lsp.stop_client(vim.lsp.get_active_clients())
 --- </pre>
 ---
 --- By default asks the server to shutdown, unless stop was requested