docs(bootstrap): Document the snarked ledger service interface

node/src/transition_frontier/sync/ledger/snarked/transition_frontier_sync_ledger_snarked_service.rs

@@ -3,24 +3,34 @@ use mina_p2p_messages::v2::{LedgerHash, MinaBaseAccountBinableArgStableV2};
 use crate::ledger::LedgerAddress;
 
 pub trait TransitionFrontierSyncLedgerSnarkedService: redux::Service {
+    /// For the given ledger, compute the merkle root hash, forcing
+    /// all pending hashes to be computed too.
     fn compute_snarked_ledger_hashes(
         &mut self,
         snarked_ledger_hash: &LedgerHash,
     ) -> Result<(), String>;
 
+    /// Creates a new copy of the ledger stored under the `origin` hash
+    /// and stores it under the `target` hash. If `overwrite` is false,
+    /// only copy the ledger if the target doesn't exist already.
     fn copy_snarked_ledger_contents(
         &mut self,
         origin: LedgerHash,
         target: LedgerHash,
         overwrite: bool,
     ) -> Result<bool, String>;
 
+    /// For the given ledger, get the two children hashes at the `parent`
+    /// address.
     fn child_hashes_get(
         &mut self,
         snarked_ledger_hash: LedgerHash,
         parent: &LedgerAddress,
     ) -> Result<(LedgerHash, LedgerHash), String>;
 
+    /// For the given ledger, sets all accounts in `accounts` under
+    /// the subtree starting at the `parent` address. The result
+    /// is the hash computed for that subtree.
     fn accounts_set(
         &mut self,
         snarked_ledger_hash: LedgerHash,