portico: Add code of conduct features to for/open-source.md.
portico: Add code of conduct features to for/open-source.md.

We got asked about this from a potential user, and they seemed fairly
excited and confused by it. In particular, it wasn't obvious that
deactivating a user was the feature they were looking for.

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