Add a "ci" feature to make clippy ignore docs warnings

plume-macro/Cargo.toml

@@ -19,3 +19,4 @@ syn = "0.15.27"
 default = []
 postgres = []
 sqlite = []
+ci = []

plume-macro/src/lib.rs

@@ -1,5 +1,5 @@
 #![recursion_limit = "128"]
-#![warn(missing_docs)]
+#![cfg_attr(not(feature = "ci"), warn(missing_docs))]
 
 #[macro_use]
 extern crate quote;