Add important note to latest changelog

Merge pull request #543 from electricbookworks/version-0-19

Update changelog and bump version number

Fix link in changelog

Update changelog and bump version number

Remove duplicate in changelog

Merge pull request #374 from electricbookworks/version-0-15-0

Update changelog, search index, and bump version number

Merge branch 'master' of github.com:electricbookworks/electric-book

Call this v0.13

Bump to version 0.12.0

Make this v0.11.1