Update README.md

Author: mtzfederico

README.md

@@ -187,6 +187,29 @@ class MyCustomCache(CacheInterface):
 handler = ipinfo.getHandler(cache=MyCustomCache())
 ```
 
+#### Accessing the cache directly
+
+You can access/update the cache directly via a dictionary-like notation with a cache_key and the handler.
+
+```python
+>>> import ipinfo
+>>> from ipinfo.handler_utils import cache_key
+>>> access_token = '123456789abc'
+>>> handler = ipinfo.getHandler(access_token)
+>>> ip_cache_key = cache_key('1.1.1.1')
+
+# Check if the ip address is in the cache
+>>> ip_cache_key in handler.cache
+True
+
+# Get the ip address's details from cache
+>>> handler.cache[ip_cache_key]
+{'ip': '1.1.1.1', 'hostname': 'one.one.one.one', 'anycast': True, 'city': 'Miami', 'region': 'Florida', 'country': 'US', 'loc': '25.7867,-80.1800', 'org': 'AS13335 Cloudflare, Inc.', 'postal': '33132', 'timezone': 'America/New_York', 'country_name': 'United States', 'latitude': '25.7867', 'longitude': '-80.1800'}
+
+# Remove the ip address from the cache
+>>> handler.cache[ip_cache_key] = None
+```
+
 ### Modifying request options
 
 **Note**: the asynchronous handler currently only accepts the `timeout` option,