Add categories to Cargo.toml

Cargo.toml

@@ -11,6 +11,7 @@ homepage = "https://github.com/rust-lang/log"
 description = """
 A lightweight logging facade for Rust
 """
+categories = ["development-tools::debugging"]
 
 [[test]]
 name = "filters"

env/Cargo.toml

@@ -10,6 +10,7 @@ description = """
 A logging implementation for `log` which is configured via an environment
 variable.
 """
+categories = ["development-tools::debugging"]
 
 [dependencies]
 log = { version = "0.3", path = ".." }