Update README.md formatting
Update README.md formatting

Minor cosmetic edits to the Bug Reporting section
igniterealtime/Spark,wrooot/Spark,guusdk/Spark,guusdk/Spark,igniterealtime/Spark,speedy01/Spark,wrooot/Spark,guusdk/Spark,speedy01/Spark,speedy01/Spark,igniterealtime/Spark,igniterealtime/Spark,guusdk/Spark,wrooot/Spark,speedy01/Spark,wrooot/Spark