docs/build-run: Fix a small wrong-name error.
docs/build-run: Fix a small wrong-name error.

This makes more sense, and is also what the link label says.
Pretty sure it's what I meant in the first place.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile