Fix typos

Found via `codespell -H`

CHANGELOG.md

@@ -26,7 +26,7 @@
 - Fixed a configuration issue with SQS storage
 
 # 0.6.1
-- Added FS-backed persistant backlog storage for persisting backlog through restarts
+- Added FS-backed persistent backlog storage for persisting backlog through restarts
 - Addressed issues with aiohttp pipe writes not being coroutine-safe
 
 # 0.6.0

README.md

@@ -109,7 +109,7 @@ PyPubSub server, which looks like this:
 ~~~json
 {"stillalive": 1588132959.6066568}
 ~~~
-Ths `stillalive` object is a simple timestamp showing, in epoch seconds, when the ping was sent.
+The `stillalive` object is a simple timestamp showing, in epoch seconds, when the ping was sent.
 
 ### Listening for events via cURL
 You can subscribe to topics via cURL like so: `curl http://localhost:2069/topics/here` where `topics/here` are the topics you are subscribing to, with `/` as a delimiter between topics. To subscribe to *all* events, you can omit the topics.