Merge pull request elastic#2550 from tsg/fix_changelog_1.3

Fixed changelog in 1.3 branch

Remove note about Npcap being (elastic#2404)

fix broken link to ingest docs (elastic#2173)

Docs version bump to alpha4 (elastic#1939)

To be merged shortly before the release.

Remove topbeat references from the doc (elastic#1777)

* Remove topbeat references from the doc

* Add variables for metricbeat

Moved one line to the bug fixes section and added a reference to the …

…pull request (elastic#1660)

workaround kafka retry deadlock elastic#1432 (elastic#1543)

* Laziliy init kafka outputs

Initialize output modes with/without guaranteed retry policy.

* Add tryPushFailed to lb/context

Updated versions for 1.2.2 release (elastic#1482)

Closed changelog for 1.2.1

Added the release notes to the docs

Merge pull request elastic#1322 from urso/cleanup-changelog

remove duplicates from changelog