Misspelled words (#625)

* Misspelled words

* Update native_executor.rs

substrate/substrate/executor/src/error.rs

@@ -40,7 +40,7 @@ error_chain! {
 			display("Invalid Code: {:?}", c),
 		}
 
-		/// Cound not get runtime version.
+		/// Could not get runtime version.
 		VersionInvalid {
 			description("Runtime version error"),
 			display("On-chain runtime does not specify version"),

substrate/substrate/executor/src/native_executor.rs

@@ -50,7 +50,7 @@ fn gen_cache_key(code: &[u8]) -> [u8; 32] {
 
 /// fetch a runtime version from the cache or if there is no cached version yet, create
 /// the runtime version entry for `code`, determines whether `Compatibility::IsCompatible`
-/// can be used by by comparing returned RuntimeVersion to `ref_version`
+/// can be used by comparing returned RuntimeVersion to `ref_version`
 fn fetch_cached_runtime_version<'a, E: Externalities<KeccakHasher>>(
 	wasm_executor: &WasmExecutor,
 	cache: &'a mut MutexGuard<CacheType>,