portico: Fix keyboard shortcuts link.
portico: Fix keyboard shortcuts link.

Changes the color of the link to learn more about keyboard
shortcuts in /features to be more readable.

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