docs: Add Apache2 reverse proxy instructions and example.
docs: Add Apache2 reverse proxy instructions and example.

Tweaked by tabbott to disable older SSL and remove websockets logic,
which isn't relevant in master.

punchagan/zulip,brainwane/zulip,timabbott/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,zulip/zulip,brainwane/zulip,rht/zulip,punchagan/zulip,showell/zulip,shubhamdhama/zulip,zulip/zulip,brainwane/zulip,zulip/zulip,eeshangarg/zulip,timabbott/zulip,rht/zulip,andersk/zulip,rht/zulip,brainwane/zulip,synicalsyntax/zulip,shubhamdhama/zulip,kou/zulip,shubhamdhama/zulip,hackerkid/zulip,shubhamdhama/zulip,zulip/zulip,brainwane/zulip,zulip/zulip,showell/zulip,rht/zulip,synicalsyntax/zulip,shubhamdhama/zulip,showell/zulip,punchagan/zulip,eeshangarg/zulip,synicalsyntax/zulip,timabbott/zulip,synicalsyntax/zulip,shubhamdhama/zulip,zulip/zulip,andersk/zulip,kou/zulip,synicalsyntax/zulip,kou/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,eeshangarg/zulip,brainwane/zulip,eeshangarg/zulip,showell/zulip,kou/zulip,kou/zulip,shubhamdhama/zulip,eeshangarg/zulip,timabbott/zulip,timabbott/zulip,andersk/zulip,punchagan/zulip,andersk/zulip,andersk/zulip,kou/zulip,hackerkid/zulip,showell/zulip,punchagan/zulip,andersk/zulip,timabbott/zulip,hackerkid/zulip,synicalsyntax/zulip,hackerkid/zulip,rht/zulip,showell/zulip,hackerkid/zulip,eeshangarg/zulip,timabbott/zulip,showell/zulip,hackerkid/zulip,kou/zulip,synicalsyntax/zulip,rht/zulip,brainwane/zulip,rht/zulip