change doc

src/data/README.md

@@ -263,14 +263,14 @@ CREATE TABLE clio.nf_token_transactions (
 
 The `nf_token_transactions` table serves as the NFT counterpart to `account_tx`, inspired by the same motivations and fulfilling a similar role within this context. It drives the `nft_history` API.
 
-### migrated_features
+### migrator_status
 
 ```
-CREATE TABLE clio.migrated_features (
-	status TEXT, 	  				# The migration status of the feature
-	feature_name TEXT,				# The name of the feature
-	PRIMARY KEY (status, feature_name)
+CREATE TABLE clio.migrator_status (
+    migrator_name TEXT,     # The name of the migrator
+    status TEXT,            # The status of the migrator
+    PRIMARY KEY (migrator_name)
 ) 
 ```
 
-The `migrated_features` table stores the status of the migration of features in this database. If a feature's status is `migrated`, it means this database has finished data migration for this feature. The feature name is the name of the feature that has been migrated. Now the status can only be `migrated`. 
+The `migrator_status` table stores the status of the migratior in this database. If a migrator's status is `migrated`, it means this database has finished data migration for this migrator.

src/migration/README.md

@@ -21,7 +21,7 @@ This command returns the current migration status of each migrator. The example
 
 
     Current Migration Status:
-    Migrator: ExampleMigrator - not migrated
+    Migrator: ExampleMigrator - Feature v1, Clio v3 - not migrated
 
 
 ### To start a migration:
@@ -30,7 +30,7 @@ This command returns the current migration status of each migrator. The example
     ./clio_server --migrate ExampleMigrator  ~/config/migrator.json
 
 
-Migration will run if the migrator has not been migrated. The migrator will be marked as migrated after the migration is completed. User can not re-run the migration for the same migrator.
+Migration will run if the migrator has not been migrated. The migrator will be marked as migrated after the migration is completed.
 
 ## How to write a migrator
 
@@ -42,6 +42,8 @@ It contains:
 
 -  A `name` which will be used to identify the migrator. User will refer this migrator in command-line tool by this name. The name needs to be different with other migrators, otherwise a compiler error will be raised.
 
+-  A `description` which is the detail information of the migrator.
+
 - A static function `runMigration`, it will be called when user run `--migrate name`. It accepts two parameters: backend, which provides the DB operations interface, and cfg, which provides migration-related configuration. Each migrator can have its own configuration under `.migration` session.
 
 - A type name alias `Backend` which specifies the backend type it supports.