Minor update on example-offchain-worker code and comment (#5970)

* Minor update on example-offchain-worker code and comment

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

* Update frame/system/src/offchain.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/frame/example-offchain-worker/src/lib.rs

@@ -45,7 +45,7 @@ use frame_system::{
 	ensure_signed,
 	ensure_none,
 	offchain::{
-		AppCrypto, CreateSignedTransaction, SendUnsignedTransaction,
+		AppCrypto, CreateSignedTransaction, SendUnsignedTransaction, SendSignedTransaction,
 		SignedPayload, SigningTypes, Signer, SubmitTransaction,
 	}
 };
@@ -381,8 +381,6 @@ impl<T: Trait> Module<T> {
 
 	/// A helper function to fetch the price and send signed transaction.
 	fn fetch_price_and_send_signed() -> Result<(), &'static str> {
-		use frame_system::offchain::SendSignedTransaction;
-
 		let signer = Signer::<T, T::AuthorityId>::all_accounts();
 		if !signer.can_sign() {
 			return Err(

substrate/frame/system/src/offchain.rs

@@ -382,6 +382,7 @@ impl<T: SigningTypes> Clone for Account<T> where
 /// ```ignore
 ///	// im-online specific crypto
 /// type RuntimeAppPublic = ImOnline(sr25519::Public);
+///
 /// // wrapped "raw" crypto
 /// type GenericPublic = sr25519::Public;
 /// type GenericSignature = sr25519::Signature;