add missing quote

Author: magnetised

README.md

@@ -367,7 +367,7 @@ The available options are:
 
 - `table` (required). The Postgres table name. Be aware of casing and [Postgres's handling of unquoted upper-case names](https://wiki.postgresql.org/wiki/Don%27t_Do_This#Don.27t_use_upper_case_table_or_column_names).
 - `namespace` (optional). The Postgres namespace that the table belongs to. Defaults to `public`.
-- `where` (optional). Filter to apply to the synced data in SQL format, e.g. `where: "amount < 1.23 AND colour in ('red', 'green')`.
+- `where` (optional). Filter to apply to the synced data in SQL format, e.g. `where: "amount < 1.23 AND colour in ('red', 'green')"`.
 - `columns` (optional). The columns to include in the synced data. By default Electric will include all columns in the table. The column list **must** include all primary keys. E.g. `columns: ["id", "title", "amount"]`.
 - `replica` (optional). By default Electric will only send primary keys + changed columns on updates. Set `replica: :full` to receive the full row, not just the changed columns.