Fix typo in README (#488)

README.md

@@ -24,7 +24,7 @@ There's a ton of them, but these are worth mentioning because they sort of affec
  * `@material-ui` - Lots of fully featured highly customizable components for building the UIs with. Theming system with global and per-component overrides of any CSS values.
  * `react-router-redux` - the newer one, 5.x.... Mindlessly simple routing with convenient global access due to redux
 
-## How things works
+## How things work
 The current playback is tracked not by storing the current offset, but instead storing the local time that the player began, the offset it began at, and the playback rate. Any time any of these values change, it rebases them all back to the current time. It means that at any arbitrary moment you can calculate the current offset with...
 ```js
 (Date.now() - state.startTime) * state.playSpeed + state.offset