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/shared.lua

@@ -190,10 +190,10 @@ function vim.tbl_contains(t, value)
   return false
 end
 
--- Returns true if the table is empty, and contains no indexed or keyed values.
---
---@see From https://github.com/premake/premake-core/blob/master/src/base/table.lua
---
+--- Checks if a table is empty.
+---
+--@see https://github.com/premake/premake-core/blob/master/src/base/table.lua
+---
 --@param t Table to check
 function vim.tbl_isempty(t)
   assert(type(t) == 'table', string.format("Expected table, got %s", type(t)))
@@ -347,13 +347,11 @@ function vim.tbl_flatten(t)
   return result
 end
 
---- Determine whether a Lua table can be treated as an array.
+--- Tests if a Lua table can be treated as an array.
 ---
---- An empty table `{}` will default to being treated as an array.
---- Use `vim.emtpy_dict()` to create a table treated as an
---- empty dict. Empty tables returned by `rpcrequest()` and
---- `vim.fn` functions can be checked using this function
---- whether they represent empty API arrays and vimL lists.
+--- Empty table `{}` is assumed to be an array, unless it was created by
+--- |vim.empty_dict()| or returned as a dict-like |API| or Vimscript result,
+--- for example from |rpcrequest()| or |vim.fn|.
 ---
 --@param t Table
 --@returns `true` if array-like table, else `false`.