Enforce heading levels increment by one.
It can be difficult to keep track of the correct heading levels in a long document. Most of the time, you want to increment heading levels by one, so inside of a heading level 1 you'll have one or more heading level 2s. If you've skipped from, for example, heading level 1 to heading level 3, that is most likely an error.
This rule warns when it finds a heading that is more than on level higher than the preceding heading.
Examples of incorrect code:
# Hello world!
### Hello world!
Goodbye World!
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#EEE Goodbye World!
If you aren't concerned with enforcing heading levels increment by one, you can safely disable this rule.