[ci skip]

Reason: WIP guides are not in the index because they are partial
work pushed to the repo. Either there is someone working on them
or else the work was interrupted.

Guides are added to the index page when they are finished, the
author considers the draft to be complete, someone reviews them,
and overall they are considered to be good for users to read.

This reverts commit eefc03a8.

added schema_migrations_table_name to ActiveRecord::Base in order that the name of the schema migrations table can be configured.

consolidated test_schema_migrations_table_name tests

Added changelog entry

edited changelog

removed commented lines

removed reader

ensure the schema migrations table is reset at end of test

added entry to configuration guide

guides typo and changelog order

[ci skip]

Also clean up some trailing spaces on line 1143-1146.

[ci skip]

Removed ```The `size` helper is an alias for `length`.``` line. If you use this "nonexist" helper, you will get an error message like this: 

```
ArgumentError: Unknown validator: 'SizeValidator'
...
```

Maybe wanted to mean ```validates_size_of``` helper as an alias for ```validates_length_of``` helper.

A small mistake found in the line of ```The default error is "can't be empty"``` for ```:presence``` helper. ```empty``` word changed to ```blank```.

Update a link to point to right section in api docs

Fix a typo

This reverts commit e5f5a838, reversing
changes made to d7567f32.

[ci skip]

Modifies the initialization guide to make the initializers process clearer and remove a TODO. [ci skip]

Minor align BR tags with HTML void - with reference to the generators code change - https://github.com/rails/rails/commit/f038d4cc5fe1ac21f92c7e32c61ff85a0c816f3f

It's confusing to not explicitly do this step.

Replace the word «Accepts» by «Accept» in the example of custom request headers.

[ci skip]

:after_initialize runs after config/initializers, not before

See `actionpack/test/controller/parameters/raise_on_unpermitted_params_test.rb`

Scaffold output: add jbuilder, update timestamp (edge guide!)

Add some file breadcrumb (comment) to help reader find files.

Improve readability by adding some command outputs.

Thanks for great help from @senny.

Getting Started Guide: update link_to string argument to use single-quote mark, following document style [ci skip]