docs: s/three functions/four functions/

Author: knpwrs

README.md

@@ -201,9 +201,8 @@ Whenever possible it is best to maintain strong safety; however, this can lead
 to extremely verbose code. For that reason this library strongly encourages
 type inference whenever possible.
 
-This library exports three functions and a handful of types. Everything you
-need is provided by one package. The API surface is very small and easy to
-grok.
+This library exports four functions and a handful of types. Everything you need
+is provided by one package. The API surface is very small and easy to grok.
 
 ### Not Too Opinionated