docs: Add code-of-conduct to the main navigation tree.
docs: Add code-of-conduct to the main navigation tree.

This quiets the last of the warnings that Sphinx was giving us about
documents not being in any toctree, now that we've explicitly told it
with `:orphan:` about the documents we intentionally don't link there.

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