docs: update News Tutorial

[kenjis]

Description

• use $this->validate() and Validation::getValidated() feat: [Validation] add method to get the validated data #7420
• add News::new() to show HTML form
• change News::view() to show()
• change routing
• add section titles

Before:

+--------+--------------+------+---------------------------------+----------------+---------------+
| Method | Route        | Name | Handler                         | Before Filters | After Filters |
+--------+--------------+------+---------------------------------+----------------+---------------+
| GET    | /            | »    | \App\Controllers\Home::index    |                | toolbar       |
| GET    | news/create  | »    | \App\Controllers\News::create   |                | toolbar       |
| GET    | news/([^/]+) | »    | \App\Controllers\News::view/$1  |                | toolbar       |
| GET    | news         | »    | \App\Controllers\News::index    |                | toolbar       |
| GET    | pages        | »    | \App\Controllers\Pages::index   |                | toolbar       |
| GET    | ([^/]+)      | »    | \App\Controllers\Pages::view/$1 |                | toolbar       |
| POST   | news/create  | »    | \App\Controllers\News::create   | csrf           | toolbar       |
+--------+--------------+------+---------------------------------+----------------+---------------+

After:

+--------+--------------+------+---------------------------------+----------------+---------------+
| Method | Route        | Name | Handler                         | Before Filters | After Filters |
+--------+--------------+------+---------------------------------+----------------+---------------+
| GET    | /            | »    | \App\Controllers\Home::index    |                | toolbar       |
| GET    | news         | »    | \App\Controllers\News::index    |                | toolbar       |
| GET    | news/new     | »    | \App\Controllers\News::new      |                | toolbar       |
| GET    | news/([^/]+) | »    | \App\Controllers\News::show/$1  |                | toolbar       |
| GET    | pages        | »    | \App\Controllers\Pages::index   |                | toolbar       |
| GET    | ([^/]+)      | »    | \App\Controllers\Pages::view/$1 |                | toolbar       |
| POST   | news         | »    | \App\Controllers\News::create   | csrf           | toolbar       |
+--------+--------------+------+---------------------------------+----------------+---------------+

Checklist:

• Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• [] Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

I find it valuable that we were using $this->request->is('post') in the previous version, but it's not a deal breaker for me. Nice update.

[kenjis]

The create() method and its explanation were too long and it was difficult to read, so I split it into two methods and defined GET and POST routes.

Then $this->request->is() is no longer needed. It would be strange to keep it, so I removed it.