docs: Explain more about how to add and remove autocmds (#105)

Co-authored-by: Adrian Wilkins <[email protected]>

lua/config/autocmds.lua

@@ -1,3 +1,8 @@
 -- Autocmds are automatically loaded on the VeryLazy event
 -- Default autocmds that are always set: https://github.com/LazyVim/LazyVim/blob/main/lua/lazyvim/config/autocmds.lua
+--
 -- Add any additional autocmds here
+-- with `vim.api.nvim_create_autocmd`
+--
+-- Or remove existing autocmds by their group name (which is prefixed with `lazyvim_` for the defaults)
+-- e.g. vim.api.nvim_del_augroup_by_name("lazyvim_wrap_spell")