doc: add rust-embed feature to docs.rs [#490]

Author: sunng87

Cargo.toml

@@ -58,5 +58,5 @@ name = "bench"
 harness = false
 
 [package.metadata.docs.rs]
-features = ["dir_source", "script_helper"]
+features = ["dir_source", "script_helper", "rust-embed"]
 rustdoc-args = ["--cfg", "docsrs"]