Spoilers minor improvements
- allow omission of space around the spoiler link text
- allow special chars in the link text
Ref: https://hive.blog/hive-196233/@tarazkp/spoilers-not-included#@quochuy/rnuclt
Ref: https://hive.blog/hive-196233/@tarazkp/spoilers-not-included#@quochuy/rnuclt