v2.0.18

Roots v2.0.18

Diff since v2.0.17

Closed issues:

• Clarify version 1.9 mention in documentation IntervalRootFinding extension for find_zeros is regarding the Julia version number (#388)
• Add link to documentation (#390)

Merged pull requests:

• add comment about what is 1.9 (julia). Close issue #388 (#389) (@jverzani)
• Change p′ to p in find_zero's docstring (#391) (@jishnub)
• Create CITATION.bib (#392) (@ya0)
• missing promotion (#394) (@jverzani)