Merge branch 'jk/doc-do-not-write-extern'

Devdoc update. * jk/doc-do-not-write-extern: CodingGuidelines: mention "static" and "extern"

Junio C Hamano committed Feb 27, 2018 at 10:33 UTC 2b0f6b1c187742ec6719478a01885ad902456f84

No changes.