add doc

Author: KazuCocoa

appium/protocols/webdriver/can_find_elements.py

@@ -12,13 +12,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import TYPE_CHECKING, Dict, List, Protocol, Union
+from typing import TYPE_CHECKING, Dict, List, Protocol, Union, runtime_checkable
 
 if TYPE_CHECKING:
     from appium.webdriver.webelement import WebElement
 
 
+@runtime_checkable
 class CanFindElements(Protocol):
+    """Protocol for objects that can find web elements.
+
+    Any class implementing this protocol must provide:
+    - find_element(by, value): Find a single element
+    - find_elements(by, value): Find multiple elements
+    """
+
     def find_element(self, by: str, value: Union[str, Dict, None] = None) -> 'WebElement': ...
 
     def find_elements(self, by: str, value: Union[str, Dict, None] = None) -> List['WebElement']: ...