Refine Topic creation for ChannelTopic and PatternTopic

[dev-jonghoonpark]

related doc: https://docs.spring.io/spring-data/redis/reference/redis/pubsub.html

Previously, the document explained that listener topics can be set using a pattern but did not mention the PatternTopic class, so this information has been added.

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[mp911de]

Thanks for reaching out. It makes sense to introduce factory methods on the Topic interface to construct ChannelTopic and PatternTopic types.

[mp911de]

Thank you for your contribution. That's merged and polished now.