add categories.

Author: dbittman

Cargo.toml

@@ -9,6 +9,7 @@ license = "MIT"
 readme = "README.md"
 description = "Map data structure keyed on (non-overlapping) ranges that allows lookup of a point within a range. Can be no_std (with use of alloc crate)."
 keywords = ["map", "no_std", "range", "interval", "tree"]
+categories = ["data-structures", "no-std"]
 [dependencies]
 
 [features]