add outlines for week 3

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

mini-lsm-book/src/week3-03-snapshot-read-part-2.md

@@ -1 +1,15 @@
 # Snapshot Read - Engine Read Path
+
+## Task 1: Store Largest Timestamp in SST
+
+## Task 2: Recover Commit Timestamp
+
+## Task 3: Lsm Iterator with Read Timestamp
+
+## Task 4: Multi-Version Scan and Get
+
+For now, inner = `Fused<LsmIterator>`, do not use `TxnLocalIterator`
+
+explain why store txn inside iterator
+
+do not implement put and delete