Document all getIncomplete implementations as returning string|false

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

lib/private/Files/Cache/Wrapper/CacheJail.php

@@ -267,7 +267,7 @@ class CacheJail extends CacheWrapper {
 	 * use the one with the highest id gives the best result with the background scanner, since that is most
 	 * likely the folder where we stopped scanning previously
 	 *
-	 * @return string|bool the path of the folder or false when no folder matched
+	 * @return string|false the path of the folder or false when no folder matched
 	 */
 	public function getIncomplete() {
 		// not supported

lib/private/Files/Cache/Wrapper/CacheWrapper.php

@@ -267,7 +267,7 @@ class CacheWrapper extends Cache {
 	 * use the one with the highest id gives the best result with the background scanner, since that is most
 	 * likely the folder where we stopped scanning previously
 	 *
-	 * @return string|bool the path of the folder or false when no folder matched
+	 * @return string|false the path of the folder or false when no folder matched
 	 */
 	public function getIncomplete() {
 		return $this->getCache()->getIncomplete();

lib/public/Files/Cache/ICache.php

@@ -243,7 +243,7 @@ interface ICache {
 	 * use the one with the highest id gives the best result with the background scanner, since that is most
 	 * likely the folder where we stopped scanning previously
 	 *
-	 * @return string|bool the path of the folder or false when no folder matched
+	 * @return string|false the path of the folder or false when no folder matched
 	 * @since 9.0.0
 	 */
 	public function getIncomplete();