Only publish for master & set docs urls

rust-bindings/rust/libostree-sys/Cargo.toml

@@ -43,6 +43,7 @@ authors = ["Felix Krull <f_krull@gmx.de>"]
 build = "build.rs"
 categories = ["external-ffi-bindings"]
 description = "FFI bindings to libostree-1"
+documentation = "https://fkrull.gitlab.io/rust-libostree/libostree_sys"
 keywords = ["ffi", "ostree", "libostree"]
 license = "MIT"
 links = "ostree"