fix url link

Author: yolossn

README.md

@@ -395,8 +395,7 @@ Note:
 I hope I did justice and helped you understand the basics of prometheus.
 
 **Where to go from here:**
-- It is important to understand PromQL extensively to take advantage of the metrics which one has collected. Remember the goal is not just to collect metrics but to derive answers for application related questions.  This
-https://medium.com/@valyala/promql-tutorial-for-beginners-9ab455142085 is a very good resource to get started with PromQL.
+- It is important to understand PromQL extensively to take advantage of the metrics which one has collected. Remember the goal is not just to collect metrics but to derive answers for application related questions.  [This](https://medium.com/@valyala/promql-tutorial-for-beginners-9ab455142085) is a very good resource to get started with PromQL.