Add links to TSDB blog post series in tsdb/README.md (#8078)

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

tsdb/README.md

@@ -2,7 +2,7 @@
 
 [![GoDoc](https://godoc.org/github.com/prometheus/prometheus/tsdb?status.svg)](https://godoc.org/github.com/prometheus/prometheus/tsdb)
 
-This repository contains the Prometheus storage layer that is used in its 2.x releases.
+This directory contains the Prometheus storage layer that is used in its 2.x releases.
 
 A writeup of its design can be found [here](https://fabxc.org/blog/2017-04-10-writing-a-tsdb/).
 
@@ -11,3 +11,9 @@ Based on the Gorilla TSDB [white papers](http://www.vldb.org/pvldb/vol8/p1816-te
 Video: [Storing 16 Bytes at Scale](https://youtu.be/b_pEevMAC3I) from [PromCon 2017](https://promcon.io/2017-munich/).
 
 See also the [format documentation](docs/format/README.md).
+
+A series of blog posts explaining different components of TSDB:
+* [The Head Block](https://ganeshvernekar.com/blog/prometheus-tsdb-the-head-block/)
+* [WAL and Checkpoint](https://ganeshvernekar.com/blog/prometheus-tsdb-wal-and-checkpoint/)
+* [Memory Mapping of Head Chunks from Disk](https://ganeshvernekar.com/blog/prometheus-tsdb-mmapping-head-chunks-from-disk/)
+* [Persistent Block and its Index](https://ganeshvernekar.com/blog/prometheus-tsdb-persistent-block-and-its-index/)