fix: Shrink crate description (#45)

Author: cakekindel

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "slack-blocks"
 version = "0.6.1"
-description = "Data structure definitions for Slack's Block Kit API - With client-side validation and helper macros"
+description = "Models + clientside validation for Slack's JSON Block Kit"
 
 edition = "2018"
 authors = ["Orion Kindel <cakekindel@gmail.com>"]