update readme (ava-labs#2644)

x/merkledb/README.md

@@ -9,8 +9,6 @@
   - [ ] Consider allowing a child view to commit into a parent view without committing to the base DB.
 - [ ] Allow concurrent reads into the trieview.
 - [ ] Remove special casing around the root node from the physical structure of the hashed tree.
-- [ ] Remove the implied prefix from the `dbNode`'s `child`
-- [ ] Fix intermediate node eviction panic when encountering errors
 - [ ] Analyze performance impact of needing to skip intermediate nodes when generating range and change proofs
   - [ ] Consider moving nodes with values to a separate db prefix
 - [ ] Replace naive concurrent hashing with a more optimized implementation