Docs: Add PHPStan type assertions

src/wp-includes/functions.php

@@ -7595,6 +7595,8 @@ function _device_can_upload() {
  *
  * @param string $path The resource path or URL.
  * @return bool True if the path is a stream URL.
+ *
+ * @phpstan-assert-if-true =non-falsy-string $path
  */
 function wp_is_stream( $path ) {
 	$scheme_separator = strpos( $path, '://' );
@@ -8227,6 +8229,7 @@ function wp_generate_uuid4() {
  *                       to accept any UUID version. Otherwise, only version allowed is `4`.
  * @return bool The string is a valid UUID or false on failure.
  *
+ * @phpstan-assert-if-true =lowercase-string&non-falsy-string $uuid
  * @phpstan-return ( $version is 4|null ? bool : false )
  */
 function wp_is_uuid( $uuid, $version = null ) {

src/wp-includes/shortcodes.php

@@ -131,6 +131,8 @@ function remove_all_shortcodes() {
  *
  * @param string $tag Shortcode tag to check.
  * @return bool Whether the given shortcode exists.
+ *
+ * @phpstan-assert-if-true =non-empty-string $tag
  */
 function shortcode_exists( $tag ) {
 	global $shortcode_tags;
@@ -148,6 +150,8 @@ function shortcode_exists( $tag ) {
  * @param string $tag     Shortcode tag to check.
  * @return bool Whether the passed content contains the given shortcode.
  *
+ * @phpstan-assert-if-true =non-falsy-string $content
+ * @phpstan-assert-if-true =non-empty-string $tag
  * @phpstan-return ( $tag is '' ? false : ( $content is empty ? false : bool ) )
  */
 function has_shortcode( $content, $tag ) {

src/wp-includes/taxonomy.php

@@ -375,6 +375,7 @@ function get_taxonomy( $taxonomy ) {
  * @param string $taxonomy Name of taxonomy object.
  * @return bool Whether the taxonomy exists.
  *
+ * @phpstan-assert-if-true =non-falsy-string $taxonomy
  * @phpstan-return ( $taxonomy is non-falsy-string ? bool : false )
  */
 function taxonomy_exists( $taxonomy ) {