docs: update tx mode gitops and more

docs/change-database/transaction-mode.mdx

@@ -30,6 +30,29 @@ For MySQL databases, Bytebase offers additional control over transaction isolati
 - **REPEATABLE READ**: Default MySQL isolation, prevents dirty and non-repeatable reads
 - **SERIALIZABLE**: Highest isolation, prevents all phenomena but may impact performance
 
+## GitOps
+
+In the GitOps workflow there is no UI toggle, so transaction mode and isolation level are controlled via comment directives at the top of the migration file:
+
+```sql
+-- txn-mode = off
+-- txn-isolation = READ COMMITTED
+
+ALTER TABLE users ADD COLUMN email VARCHAR(255);
+```
+
+Supported directives:
+
+- `-- txn-mode = on|off` — wrap the script in a transaction, or run statements directly without transaction wrapping
+- `-- txn-isolation = READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE` — MySQL only
+
+Rules:
+
+- Directives must appear at the top of the file, before any non-comment SQL
+- Empty lines between directives are allowed; scanning stops at the first non-comment line
+- The order of the two directives does not matter
+- Whitespace around `=` is optional — `-- txn-mode = off` and `-- txn-mode=off` are both accepted; the spaced form shown above is the canonical style
+
 ## Best Practices
 
 - Keep transactions enabled for DDL and DML operations that modify data

docs/gitops/migration-based-workflow/develop.mdx

@@ -81,12 +81,18 @@ Choose a versioning strategy that fits your team:
 For zero-downtime MySQL schema changes, add this comment at the top of your file:
 
 ```sql
--- migration-type: ghost
+-- gh-ost = {}
 
 ALTER TABLE users ADD COLUMN email VARCHAR(255);
 ```
 
-This uses [gh-ost](https://github.com/github/gh-ost) to apply changes without blocking your database.
+This uses [gh-ost](https://github.com/github/gh-ost) to apply changes without blocking your database. Use `{}` to run with default flags, or pass gh-ost flags as a JSON object:
+
+```sql
+-- gh-ost = {"max-lag-millis":"1500","cut-over-lock-timeout-seconds":"10"}
+
+ALTER TABLE users ADD COLUMN email VARCHAR(255);
+```
 
 <Card title="Online Schema Migration" icon="bolt" href="/change-database/online-schema-migration-for-mysql">
   Learn more about gh-ost