Add the wasm crates.io category

Author: fitzgen

wee_alloc/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 authors = ["Nick Fitzgerald <fitzgen@gmail.com>"]
-categories = ["memory-management", "web-programming", "no-std"]
+categories = ["memory-management", "web-programming", "no-std", "wasm"]
 description = "wee_alloc: The Wasm-Enabled, Elfin Allocator"
 license = "MPL-2.0"
 name = "wee_alloc"