Add instructions for building docs using Readthedocs Docker container

CONTRIBUTING.md

@@ -48,8 +48,22 @@ $ open docs/_build/index.html
 $ xdg-open docs/_build/index.html
 ```
 
-Documentation is automatically built by ReadTheDocs whenever code is merged into the `main` branch.
+### Readthedocs
+Documentation is automatically built by Readthedocs whenever code is merged into the `main` branch.
 
+Sometimes, there are differences in the Readthedocs build environment that can cause builds to
+succeed locally but fail remotely. To help debug this, you can use the Readthedocs Docker container
+(`readthedocs/build`) to perform the build. Example:
+```bash
+docker pull readthedocs/build
+docker run --rm -ti \
+  -v (pwd):/home/docs/project \
+  readthedocs/build \
+  /bin/bash -c \
+  "cd /home/docs/project \
+    && pip3 install '.[dev]' \
+    && make -C docs html"
+```
 
 ## Releases
 Releases are built and published to pypi based on **git tags.**

aiohttp_client_cache/backends/base.py

@@ -29,10 +29,10 @@ class CacheBackend:
 
     Args:
         cache_name: Cache prefix or namespace, depending on backend; see notes below
-        expire_after: Number of hours after which a cache entry will expire; se ``None`` to
+        expire_after: Number of hours after which a cache entry will expire; set to ``None`` to
             never expire
-        allowed_codes: Limit caching only for response with this codes
-        allowed_methods: Cache only requests of this methods
+        allowed_codes: Only cache responses with one of these codes
+        allowed_methods: Cache only responses for one of these HTTP methods
         include_headers: Make request headers part of the cache key
         ignored_params: List of request parameters to be excluded from the cache key.
         filter_fn: function that takes a :py:class:`aiohttp.ClientResponse` object and
@@ -54,7 +54,7 @@ class CacheBackend:
     def __init__(
         self,
         cache_name: str = 'aiohttp-cache',
-        expire_after: Union[int, timedelta] = None,
+        expire_after: Union[int, float, timedelta] = None,
         allowed_codes: tuple = (200,),
         allowed_methods: tuple = ('GET', 'HEAD'),
         include_headers: bool = False,