Fix indenting in CHANGELOG for consistency
Fix indenting in CHANGELOG for consistency

Fix indenting in `CHANGELOG.md` for consistency with other tools[1][2].

[1]:
https://raw.githubusercontent.com/alphagov/vcloud-edge_gateway/master/CHANGELOG.md
[2]:
https://raw.githubusercontent.com/alphagov/vcloud-launcher/master/CHANGELOG.md

gds-operations/vcloud-net_launcher,gds-operations/vcloud-net_launcher,gds-operations/vcloud-net_launcher