Docs: Example for blueprint step `writeFile` flushes permalink rewrites rules on every page load

[eliot-akira]

Making a note of something I noticed in the documentation.

• https://wordpress.github.io/wordpress-playground/guides/for-theme-developers/#writefile

The example for the blueprint step writeFile shows how to create a mu-plugin that enables pretty permalinks.

{
  "step": "writeFile",
  "path": "/wordpress/wp-content/mu-plugins/rewrite.php",
  "data": "<?php /* Use pretty permalinks */ add_action( 'after_setup_theme', function() { global $wp_rewrite; $wp_rewrite->set_permalink_structure('/%postname%/'); $wp_rewrite->flush_rules(); } );"
}

Expanding the code:

<?php
/* Use pretty permalinks */
add_action( 'after_setup_theme', function() {
  global $wp_rewrite;
  $wp_rewrite->set_permalink_structure('/%postname%/');
  $wp_rewrite->flush_rules();
} );

The after_setup_theme action is called on every page load, so it's not the best way to enable pretty permalinks and flush rewrite rules (which is considered an "expensive" operation).

A better way is to do it once using the runPHP step.

{
  "step": "runPHP",
  "code": "<?php include '/var/www/html/wp-load.php'; global $wp_rewrite; $wp_rewrite->set_permalink_structure('/%postname%/'); $wp_rewrite->flush_rules();"
},

There might be a simpler way to achieve it. This PR seems to have made pretty permalinks the default.

• Prefer pretty permalinks like WP install does #1832

update_option('permalink_structure', '/%year%/%monthnum%/%day%/%postname%/');

This method does not flush rewrite rules. Maybe it's not needed because it's always run on a freshly created site.

Anyway, if the default is to use pretty permalinks, then the above mentioned example in the docs is unnecessary and could be removed altogether.