Update general expiration docs

docs/user_guide/expiration.md

diff --git a/docs/user_guide/expiration.md b/docs/user_guide/expiration.md
index f6a90aa..767b220 100644
--- a/docs/user_guide/expiration.md
+++ b/docs/user_guide/expiration.md
@@ -114,12 +114,10 @@
 for more details on request errors in general.
 
 ## Removing Expired Responses
+
+### Manual Removal
 For better read performance, expired responses won't be removed immediately, but will be removed
 (or replaced) the next time they are requested.
-:::{tip}
-Implementing one or more cache eviction algorithms is being considered. If this is something you are
-interested in, please provide feedback via [issues](https://github.com/reclosedev/requests-cache/issues)!
-:::
 
 To manually clear all expired responses, use
 {py:meth}`.CachedSession.remove_expired_responses`:
@@ -127,7 +125,7 @@
 >>> session.remove_expired_responses()
 ```
 
-Or, when using patching:
+Or, if you are using {py:func}`.install_cache`:
 ```python
 >>> requests_cache.remove_expired_responses()
 ```
@@ -137,6 +135,16 @@
 >>> session.remove_expired_responses(expire_after=timedelta(days=30))
 ```
 
+### Automatic Removal
+The following backends have native TTL support, which can be used to automatically remove expired
+responses:
+* {py:mod}`MongoDB <requests_cache.backends.mongodb>`
+* {py:mod}`Redis <requests_cache.backends.redis>`
+<!--
+TODO: Not yet supported:
+* {py:mod}`DynamoDB <requests_cache.backends.dynamodb>`
+-->
+
 ## Request Options
 In addition to the base arguments for {py:func}`requests.request`, requests-cache adds some extra
 cache-related arguments. These apply to {py:meth}`.CachedSession.request`,

requests_cache/backends/dynamodb.py

diff --git a/requests_cache/backends/dynamodb.py b/requests_cache/backends/dynamodb.py
index 711022e..2ec971a 100644
--- a/requests_cache/backends/dynamodb.py
+++ b/requests_cache/backends/dynamodb.py
@@ -16,6 +16,8 @@
     DynamoDB binary item sizes are limited to 400KB. If you need to cache larger responses, consider
     using a different backend.
 
+
+
 Creating Tables
 ^^^^^^^^^^^^^^^
 Tables will be automatically created if they don't already exist. This is convienient if you just

requests_cache/patcher.py

diff --git a/requests_cache/patcher.py b/requests_cache/patcher.py
index 5678b7f..dd81f67 100644
--- a/requests_cache/patcher.py
+++ b/requests_cache/patcher.py
@@ -1,4 +1,4 @@
-"""Utilities for patching ``requests``.
+"""Utilities for patching ``requests``. See :ref:`patching` for general usage info.
 
 .. warning:: These functions are not thread-safe. Use :py:class:`.CachedSession` if you want to use
     caching in a multi-threaded environment.