docs: audit MongoDB and Redis module pages

[demengc]

Summary

• MongoDB: Added dependency snippet, credentials field table, ConfigurationSection factory method docs, API reference table (getClient(), getDatabase(), getDatabase(String), close()), corrected Terminable (was AutoCloseable), reordered sections (Queries/Indexes before Complete Example).
• Redis: Documented both AsyncRedisMessageReceiveEvent and RedisMessageReceiveEvent (previously only async was shown), documented constructor varargs channels parameter, added credentials field table with nullable column, added ConfigurationSection factory method docs, added full API reference table (including subscribe, unsubscribe, isSubscribed, return types), added event properties table (getSenderId, getMessage, getMessageObject, getTimestamp), corrected Terminable (was AutoCloseable), fixed thread-safety issue in examples (Bukkit API calls now use sync event).
• Both pages now include Maven dependency snippets with current version (1.36.1-SNAPSHOT) and mention the shaded library versions (MongoDB driver 5.6.1, Jedis 7.0.0).

Test plan

• Verify all method names, parameter types, and return types match the source code
• Verify code examples compile against the current API
• Confirm GitBook renders markdown tables correctly