README: Fix link to now- obsolete 1.7.1 release.
README: Fix link to now- obsolete 1.7.1 release.

We should really be linking to the latest stable release.

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