Rename the main plugin file

[dkotter]

Description of the Change

Renames the main plugin file from plugin.php to block-catalog.php and updates any places that referenced that.

Also updates the contributing instructions a bit.

Closes #12

How to test the Change

Verify all changes look correct in this PR and that the plugin still loads

Changelog Entry

Changed - Updated the main plugin file name. Note that this change will require the plugin to be reactivated after updating.

Credits

Props @dkotter

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[peterwilsoncc]

The active plugins are stored in the WP database as plugin-directory/file.php so plugin.php will need to retained for sites that have block-catalog/plugin.php active.

Completely untested but I think the file can contain something like this:

function update_active_plugin() {
   $old_name = basename( __DIR__ ) . '/plugin.php';
   $new_name = basename( __DIR__ ) . '/block-catalog.php';

  $active_plugins = get_option( 'active_plugins', array() );

  foreach ( $active_plugins as $key => $active_plugin ) {
	if ( $old_name = $active_plugin ) {
		$active_plugins[$key] = $new_name;
	}
  }

  update_option( 'active_plugins', $active_plugins );
}

add_action( 'plugins_loaded', __NAMESPACE__ . '\\update_active_plugin' );

[dsawardekar]

PR Looks good to me, @dkotter . @peterwilsoncc 's note is interesting, but I would avoid changing active_plugins. Given that this plugin is admin-only, I would just add a note to the changelog asking folks to reactivate.