api docs: Fix link to IFTTT.
api docs: Fix link to IFTTT.

Old link is 404'ing.

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