Small doc updates.

Author: thedodd

wither/Cargo.toml

@@ -24,7 +24,7 @@ lazy_static = "1"
 wither_derive = { version = "0.6", path = "../wither_derive" }
 
 [features]
-docinclude = [] # Used only for activating `doc(include="...")` on stable.
+docinclude = [] # Used only for activating `doc(include="...")` on nightly.
 
 [package.metadata.docs.rs]
 features = ["docinclude"] # Activate `docinclude` during docs.rs build.