Start release notes.
Some updates to release note links.
Update basic RMA guide.
Remove extendable line items from notes.
Fix example to contain expectation
Fixes #5449
allow guests to use the payments api for their orders
Fixes #5450
Improve localization of stock_locations/_form
Fixes #5454
Fix factories to generate unique SKUs

* Choosing random SKUs even from a high range can yield duplicates
  resulting in build failures.
* Kernel.rand(9999) was definitively never a good choice due the
  birthday paradoxon lets manifest a duplicate quite often
* Uses sequencially generated SKUs defined from a single shared and
  reusable generator.

Fixes #5452
Fix problems with “database: true” on Teatro
Fixes #5457
label values for payment methods form

remove unused fullwidth class

It appears the button was loading as `<button class="fa fa-plus button"
name="button" type="{:class=>&quot;fullwidth&quot;}">Add</button>`
which isn’t very pretty.

bind numerous label tags to their inputs

add labels and move inputs onto single row

The quantity input was taking u pa whole row and so was the variant
input. A bit too long to look nice. Made it a lot more aesthetic and
add the label tags.

tab width with 2 spaces, not 4 spaced tab

use and instead of &amp;

the &amp; was not encoding, so I just switched to and.

add a page title for taxons

add taxons to products tab

update the adjustment button style

get more of the label tags matching

Fixes #5446
Fix regression from 9d12f0e