Reference: https://github.com/rails/rails/commit/d4fd0bd17709735ac91e434c94fe99429f078c6e

cc @schneems

Reference: https://github.com/rails/rails/commit/f7e4362011ceb1317fd401125d48d7ccb9a1079c

This reverts commit 0f6b101e.

Reason: It's better to let `unscope` be documented. We can add a
separate section for `except`.

The example showed is `except`, however the method "documented" is `unstop`. Fix to align the docs to the example.

Also use appropriate mailer syntax in the `find_each` block.

Put all options for overloading `find` in one section

Add docs on what happens when a numerical argument is provided to last.

Since `last!` behaves exactly the same way but can raise an argument we can consolidate it in the `last` section.

Add docs on what happens when a numerical argument is provided to take.

Since `take!` behaves exactly the same way but can raise an argument we can consolidate it in the `take` section.

Since `find_by!` behaves exactly the same way but can raise an argument we can consolidate it in the `find_by` section.

Add docs for `first` when provided a numerical argument. 

Since `first!` behaves exactly the same way but can raise an argument we can consolidate it in the `first` section.

Closes #15541.

duplicating API reference in guides. Also ✂ [ci skip]

[ci skip]

In Active Record Querying guide, currently `Merging of scopes` section uses a concept of default scope in its example before it is introduced in the following section titled `Applying a default scope`.

It makes more sense to switch the ordering to introduce default scopes (`Applying a default scope`) first and then go into `Merging of scopes` section where it is used.

[ci skip]

find_by_* and find_by_*! are not deprecated for example, so lets add a
note only where it is needed

[ci skip]

he or she => they

I'm pretty confused about the addition of this method. The documentation
says that it was intended to allow the removal of values from the
default scope (in contrast to #except). However it behaves exactly the
same as except: https://gist.github.com/jonleighton/7537008 (other than
having a slightly enhanced syntax).

The removal of the default scope is allowed by
94924dc3, which was not a change we
could make until 4.1 due to the need to deprecate things. However after
that change #unscope still gives us nothing that #except doesn't already
give us.

However there *is* a desire to be able to unscope stuff in a way that
persists across merges, which would allow associations to be defined
which unscope stuff from the default scope of the associated model. E.g.

  has_many :comments, -> { unscope where: :trashed }

So that's what this change implements. I've also corrected the
documentation. I removed the guide references to #except as I think
unscope really supercedes #except now.

While we're here, there's also a potential desire to be able to write
this:

  has_many :comments, -> { unscoped }

However, it doesn't make sense and would not be straightforward to
implement. While with #unscope we're specifying exactly what we want to
be removed from the relation, with "unscoped" we're just saying that we
want it to not have some things which were added earlier on by the
default scope. However in the case of an association, we surely don't
want *all* conditions to be removed, otherwise the above would just
become "SELECT * FROM comments" with no foreign key constraint.

To make the above work, we'd have to somehow tag the relation values
which get added when evaluating the default scope in order to
differentiate them from other relation values. Which is way too much
complexity and therefore not worth it when most use cases can be
satisfied with unscope.

Closes #10643, #11061.

```yaml
Revert "syntax error joining/including models"

This reverts commit ac35f72f.
```

Revert "syntax error joining tables"

This reverts commit c365986b.

---

Comments:

https://github.com/rails/docrails/commit/c365986b48c3e8bc8c7f3fa6a8521616ed5dc138#commitcomment-4630684

syntax error joining/including models

syntax error joining tables

[ci skip] Correct the explanation of the example for find_or_create_by when used with create_with in ActiveRecord Querying guide