Docs: Remove @static notations from property DocBlocks in wp-admin/* and wp-includes/* classes.

This tag has been used in the past, but should no longer be used. Just using the `static` keyword in code is enough for PhpDocumentor on PHP5+ to recognize static variables and methods, and PhpDocumentor will mark them as static.

Props birgire.
See #42803.

git-svn-id: https://develop.svn.wordpress.org/trunk@42747 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-customize-section.php

@@ -24,8 +24,6 @@ class WP_Customize_Section {
 	 * Used when sorting two instances whose priorities are equal.
 	 *
 	 * @since 4.1.0
-	 *
-	 * @static
 	 * @var int
 	 */
 	protected static $instance_count = 0;