Update README.

jmjoy · jmjoy · commit bf98f75f5862 · 2020-10-31T00:29:34.000+08:00
diff --git a/README.md b/README.md
@@ -6,6 +6,7 @@ A library that allows us to write PHP extensions using pure Rust and using safe
 
 ## Requirement
 
+- rust nightly channel (now)
 - libclang >= 9
 
 ## Usage
