docs: clarify using opts = {} vs config = function() ... require('plu… (nvim-lua#1316)

* docs: clarify using opts = {} vs config = function() ... require('plugin').setup({}) .. end

The current documentation mentioning that using "require" is equivalent to using "opts" without detailing the use in the "config = function()" block seems inaccurate.
Lower in the configuration the "config = function()" block is used without clarifying why it needed and what it does.
This clarification may help new users understand the difference between the two, or how and where to place the "require" statement.

* Update init.lua

* remove whitespace

Author: bleacheda