Documentation is a mess

[Destroy666x]

Here are some obvious issues I spotted:

• https://nest-modules.github.io/mailer/ isn't even up-to-date with

  mailer/docs/mailer.md

  Line 488 in 248e829

  You can use [mjml](https://mjml.io/) to create responsive emails with the `MjmlAdapter` adapter. The templates themselves still need to be pre-rendered with pug, handlebars or ejs.

  - MJML isn't mentioned
• Lots of options are undocumented and some of the documented ones are unclear, e.g. why does MJMLAdapter need inlineCssEnabled to be false? How to use partials, other than configuring them? Can you even use Handlebars partials with MJML? 0 explantation.