doc: Add short comment about example in README.md is compiled and run

jhg · jhg · commit d13d5a7e23b0 · 2021-04-18T21:25:51.000+02:00
diff --git a/src/lib.rs b/src/lib.rs
@@ -1,5 +1,5 @@
 #![feature(external_doc)]
-#![doc(include = "../README.md")]
+#![doc(include = "../README.md")] // This also allow to run examples in that file.
 
 #![allow(unsafe_code)]
 #![warn(missing_docs)]
