docs: Update changelog since 1.8.1 release.
docs: Update changelog since 1.8.1 release.

brainwane/zulip,synicalsyntax/zulip,showell/zulip,rishig/zulip,punchagan/zulip,rht/zulip,synicalsyntax/zulip,kou/zulip,tommyip/zulip,kou/zulip,synicalsyntax/zulip,dhcrzf/zulip,andersk/zulip,andersk/zulip,rht/zulip,rishig/zulip,shubhamdhama/zulip,tommyip/zulip,showell/zulip,hackerkid/zulip,brainwane/zulip,timabbott/zulip,zulip/zulip,punchagan/zulip,shubhamdhama/zulip,shubhamdhama/zulip,dhcrzf/zulip,punchagan/zulip,zulip/zulip,timabbott/zulip,dhcrzf/zulip,kou/zulip,kou/zulip,punchagan/zulip,andersk/zulip,brainwane/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,eeshangarg/zulip,showell/zulip,synicalsyntax/zulip,hackerkid/zulip,jackrzhang/zulip,andersk/zulip,zulip/zulip,synicalsyntax/zulip,shubhamdhama/zulip,showell/zulip,eeshangarg/zulip,timabbott/zulip,andersk/zulip,brainwane/zulip,hackerkid/zulip,rishig/zulip,jackrzhang/zulip,rishig/zulip,tommyip/zulip,rht/zulip,hackerkid/zulip,rht/zulip,brainwane/zulip,timabbott/zulip,timabbott/zulip,hackerkid/zulip,timabbott/zulip,rht/zulip,showell/zulip,kou/zulip,synicalsyntax/zulip,jackrzhang/zulip,jackrzhang/zulip,eeshangarg/zulip,jackrzhang/zulip,hackerkid/zulip,showell/zulip,rht/zulip,eeshangarg/zulip,tommyip/zulip,zulip/zulip,rishig/zulip,jackrzhang/zulip,zulip/zulip,synicalsyntax/zulip,zulip/zulip,shubhamdhama/zulip,tommyip/zulip,shubhamdhama/zulip,punchagan/zulip,shubhamdhama/zulip,kou/zulip,andersk/zulip,dhcrzf/zulip,jackrzhang/zulip,dhcrzf/zulip,eeshangarg/zulip,tommyip/zulip,dhcrzf/zulip,timabbott/zulip,hackerkid/zulip,eeshangarg/zulip,showell/zulip,brainwane/zulip,kou/zulip,punchagan/zulip,rishig/zulip,tommyip/zulip,dhcrzf/zulip,rht/zulip,brainwane/zulip,rishig/zulip,punchagan/zulip