Minor improvements in README
Minor improvements in README

- removed username from URL while cloning as its not necessary and command now can be copy-pasted.
- removed separator after heading 2.
intel-hadoop/Big-Data-Benchmark-for-Big-Bench,XiaominZhang/Big-Data-Benchmark-for-Big-Bench,XiaominZhang/Big-Data-Benchmark-for-Big-Bench,philjjoon/Big-Data-Benchmark-for-Big-Bench,philjjoon/Big-Data-Benchmark-for-Big-Bench,intel-hadoop/Big-Data-Benchmark-for-Big-Bench