Merge pull request #11784 from davetoxa/patch-2

Bump ruby version [ci skip]
RDoc tweaks
skip `test_unicode_column_name` for `MysqlAdapter`.

This commit fixes the build but we need to further investigate the root cause,
to see if it can be fixed.

The test fails under `MysqlAdapter` with:

```
ActiveRecord::UnknownAttributeError: unknown attribute: なまえ
```

The root cause is that the returned column names from the adapter
have the wrong encoding:

```ruby
columns = Weird.columns_hash.keys
columns # => ["id", "a$b", "\xE3\x81\xAA\xE3\x81\xBE\xE3\x81\x88", "from"]
columns.map(&:encoding) # => [#<Encoding:ASCII-8BIT>, #<Encoding:ASCII-8BIT>, #<Encoding:ASCII-8BIT>, #<Encoding:ASCII-8BIT>]
columns.map {|c| c.dup.force_encoding "utf-8"} # => ["id", "a$b", "なまえ", "from"]
```

From what I can tell the MySQL variables are fine:

```
ActiveRecord::Base.connection.execute("show variables")

...
character_set_client utf8
character_set_connection utf8
character_set_database utf8
character_set_filesystem binary
character_set_results utf8
character_set_server utf8
character_set_system utf8
character_sets_dir /usr/local/Cellar/mysql/5.5.29/share/mysql/charsets/
collation_connection utf8_general_ci
collation_database utf8_unicode_ci
collation_server utf8_general_ci
...
```
Avoid defining multibyte method names in JSON decoding test for JRuby Compat

This change is similar to #11736 & in same way switched with fixed string & the index of the hash for method name. the index was added because otherwise, ruby will raise Error.
document how to deploy to a subdirectory. #2992 [ci skip]
Merge pull request #10045 from senny/document_relative_url_root

document how to deploy to a subdirectory [ci skip]
Merge pull request #11789 from gaurish/multibyte_methods

Avoid defining multibyte method names in JSON decoding test for JRuby Compatitibility
Fix multidimensional PG arrays containing non-string items
Minor align BR tags with HTML void - with reference to the generators code change - https://github.com/rails/rails/commit/f038d4cc5fe1ac21f92c7e32c61ff85a0c816f3f
let the sqlite task run without rails
use `skip` so we can see what tests are not run
Merge pull request #11331 from vipulnsward/remove_conditional

Remove conditional, results are always an instance of `ActiveRecord::Result`
cast hstore values on write to be consistent with reading from the db.
Set field encoding to client_encoding for mysql adapter.
Merge pull request #11802 from ko1/fix_field_encoding_for_mysql

Set field encoding to client_encoding for mysql adapter.
Remove using of suffix with term. [ci skip]
Merge pull request #11806 from jetthoughts/change_model_term_by_simple_word

Remove using of suffix with term. [ci skip]
Add tests for ActiveModel::Serializers::JSON#as_json ordering
Fix a broken link
Merge pull request #11815 from yaotti/patch-1

Fix a broken link [ci skip]