docs: s/tutorial/course

Signed-off-by: Alex Chi Z <iskyzh@gmail.com>

mini-lsm-starter/src/block.rs

@@ -29,7 +29,7 @@ pub struct Block {
 }
 
 impl Block {
-    /// Encode the internal data to the data layout illustrated in the tutorial
+    /// Encode the internal data to the data layout illustrated in the course
     /// Note: You may want to recheck if any of the expected field is missing from your output
     pub fn encode(&self) -> Bytes {
         unimplemented!()

mini-lsm-starter/src/lsm_iterator.rs

@@ -22,7 +22,7 @@ use crate::{
     mem_table::MemTableIterator,
 };
 
-/// Represents the internal type for an LSM iterator. This type will be changed across the tutorial for multiple times.
+/// Represents the internal type for an LSM iterator. This type will be changed across the course for multiple times.
 type LsmIteratorInner = MergeIterator<MemTableIterator>;
 
 pub struct LsmIterator {