[skip ci] Align README and Docs with the new description

Author: kateinoigakukun

README.md

@@ -2,7 +2,7 @@
 
 # WasmKit
 
-**WasmKit** is a standalone WebAssembly runtime written in Swift.
+**WasmKit** is a standalone and embeddable WebAssembly runtime implementation written in Swift.
 
 ## Usage
 

Sources/WasmKit/Docs.docc/Docs.md

@@ -4,7 +4,7 @@ A WebAssembly runtime written in Swift.
 
 ## Overview
 
-WasmKit is a standalone and embeddable WebAssembly runtime implementation for Swift.
+**WasmKit** is a standalone and embeddable WebAssembly runtime implementation written in Swift.
 
 
 ## Quick start