Fix more docs.

Author: arik-so

lightning-block-sync/src/init.rs

@@ -59,7 +59,7 @@ where
 ///
 /// use lightning_block_sync::*;
 ///
-/// use std::io::Cursor;
+/// use lightning::io::Cursor;
 ///
 /// async fn init_sync<
 /// 	B: BlockSource,

lightning-invoice/src/lib.rs

@@ -148,7 +148,6 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY_DELTA: u64 = 18;
 /// ensures that only a semantically and syntactically correct invoice can be built using it.
 ///
 /// ```
-/// extern crate secp256k1;
 /// extern crate lightning;
 /// extern crate lightning_invoice;
 /// extern crate bitcoin;