Add URI to the documentation

w/o it, a link to the doc was not shown in the search page of crates.io.

Author: dynaxis

macros/Cargo.toml

@@ -6,6 +6,7 @@ authors = ["CodeChain Team <[email protected]>"]
 license = "MIT OR Apache-2.0"
 edition = "2018"
 repository = "https://github.com/CodeChain-io/intertrait"
+documentation = "https://docs.rs/intertrait"
 include = ["src/**/*", "Cargo.toml", "LICENSE-*"]
 
 [lib]