docs: Add some basic coverage of our mypy Python 3 situation.
docs: Add some basic coverage of our mypy Python 3 situation.

punchagan/zulip,tommyip/zulip,synicalsyntax/zulip,dhcrzf/zulip,eeshangarg/zulip,showell/zulip,zulip/zulip,timabbott/zulip,zulip/zulip,eeshangarg/zulip,mahim97/zulip,tommyip/zulip,rishig/zulip,punchagan/zulip,mahim97/zulip,eeshangarg/zulip,shubhamdhama/zulip,showell/zulip,showell/zulip,andersk/zulip,brainwane/zulip,tommyip/zulip,rht/zulip,brainwane/zulip,andersk/zulip,zulip/zulip,andersk/zulip,brainwane/zulip,dhcrzf/zulip,dhcrzf/zulip,jackrzhang/zulip,rishig/zulip,synicalsyntax/zulip,jackrzhang/zulip,rht/zulip,andersk/zulip,dhcrzf/zulip,punchagan/zulip,synicalsyntax/zulip,rht/zulip,rishig/zulip,timabbott/zulip,tommyip/zulip,kou/zulip,punchagan/zulip,kou/zulip,rishig/zulip,shubhamdhama/zulip,synicalsyntax/zulip,timabbott/zulip,eeshangarg/zulip,shubhamdhama/zulip,kou/zulip,zulip/zulip,brainwane/zulip,shubhamdhama/zulip,tommyip/zulip,hackerkid/zulip,hackerkid/zulip,andersk/zulip,jackrzhang/zulip,rishig/zulip,brainwane/zulip,kou/zulip,synicalsyntax/zulip,showell/zulip,showell/zulip,andersk/zulip,timabbott/zulip,eeshangarg/zulip,mahim97/zulip,rht/zulip,timabbott/zulip,rishig/zulip,brainwane/zulip,kou/zulip,tommyip/zulip,timabbott/zulip,synicalsyntax/zulip,rht/zulip,zulip/zulip,hackerkid/zulip,jackrzhang/zulip,rht/zulip,jackrzhang/zulip,hackerkid/zulip,dhcrzf/zulip,hackerkid/zulip,punchagan/zulip,shubhamdhama/zulip,dhcrzf/zulip,mahim97/zulip,punchagan/zulip,mahim97/zulip,kou/zulip,rht/zulip,hackerkid/zulip,zulip/zulip,dhcrzf/zulip,hackerkid/zulip,showell/zulip,eeshangarg/zulip,jackrzhang/zulip,punchagan/zulip,andersk/zulip,kou/zulip,showell/zulip,tommyip/zulip,eeshangarg/zulip,zulip/zulip,rishig/zulip,jackrzhang/zulip,timabbott/zulip,shubhamdhama/zulip,shubhamdhama/zulip,brainwane/zulip,mahim97/zulip,synicalsyntax/zulip