DOC: fix minor docstring grammar in events.py (#3783)

This PR fixes a few small docstring grammar issues in
`ignite/engine/events.py`. There are **no code or behavior changes**,
only wording fixes in comments/docstrings.

All changes are minimal and localized, for example:

```python
# Before
"""Single Event containing a filter, specifying whether the event should
be run at the current event (if the event type is correct)

Args:
    value: The actual enum value. Only needed for internal use. Do not touch!
    event_filter: A function taking the engine and the current event value as input and returning a
        boolean to indicate whether this event should be executed. Defaults to None, which will result to a
        function that always returns `True`
    name: The enum-name of the current object. Only needed for internal use. Do not touch!
"""
```

```python
# After
"""Single event containing a filter specifying whether the handler should be run for the current event (if the event type is correct).

Args:
    value: The actual enum value. Only needed for internal use. Do not touch!
    event_filter: A function taking the engine and the current event value as input and returning a
        boolean to indicate whether this event should be executed. Defaults to None, which will result in a
        function that always returns `True`.
    name: The enum-name of the current object. Only needed for internal use. Do not touch!
"""
```

The deprecated default event filter docstring is also cleaned up: [is
is]

```python
# Before
"""Default event filter. This method is is deprecated and will be removed. Please, use None instead"""

# After
"""Default event filter. This method is deprecated and will be removed. Please use None instead."""
```

These changes:

- Fix a duplicated word: `is is`.
- Replace “result to” with the correct “result in”.
- Make the `CallableEventWithFilter` docstring clearer and grammatically
correct.
- Fixed: "User can also combine events" --> "Users can also ..."

Author: importstring

ignite/engine/events.py

@@ -23,7 +23,7 @@ class CallableEventWithFilter:
     Args:
         value: The actual enum value. Only needed for internal use. Do not touch!
         event_filter: A function taking the engine and the current event value as input and returning a
-            boolean to indicate whether this event should be executed. Defaults to None, which will result to a
+            boolean to indicate whether this event should be executed. Defaults to None, which will result in a
             function that always returns `True`
         name: The enum-name of the current object. Only needed for internal use. Do not touch!
     """
@@ -178,7 +178,7 @@ def wrapper(engine: "Engine", event: int) -> bool:
 
     @staticmethod
     def default_event_filter(engine: "Engine", event: int) -> bool:
-        """Default event filter. This method is is deprecated and will be removed. Please, use None instead"""
+        """Default event filter. This method is deprecated and will be removed. Please, use None instead"""
         warnings.warn("Events.default_event_filter is deprecated and will be removed. Please, use None instead")
         return True
 
@@ -347,7 +347,7 @@ def call_every_itr_before_after(engine):
     Event filter function `event_filter` accepts as input `engine` and `event` and should return True/False.
     Argument `event` is the value of iteration or epoch, depending on which type of Events the function is passed.
 
-    Since v0.4.0, user can also combine events with `|`-operator:
+    Since v0.4.0, users can also combine events with `|`-operator:
 
     .. code-block:: python