docs: specify the updated LsmIterator::new constructor signature (#150)

mini-lsm-starter/src/block/builder.rs

@@ -38,6 +38,7 @@ impl BlockBuilder {
     }
 
     /// Adds a key-value pair to the block. Returns false when the block is full.
+    /// You may find the `bytes::BufMut` trait useful for manipulating binary data.
     #[must_use]
     pub fn add(&mut self, key: KeySlice, value: &[u8]) -> bool {
         unimplemented!()

mini-lsm-starter/src/table/builder.rs

@@ -57,7 +57,7 @@ impl SsTableBuilder {
 
     /// Builds the SSTable and writes it to the given path. Use the `FileObject` structure to manipulate the disk objects.
     pub fn build(
-        self,
+        mut self,
         id: usize,
         block_cache: Option<Arc<BlockCache>>,
         path: impl AsRef<Path>,