docs: add statefulSet analyzer in the docs. (#233)

Signed-off-by: Aris Boutselis <aris.boutselis@senseon.io>
Signed-off-by: Alex Jones <alexsimonjones@gmail.com>

README.md

@@ -140,6 +140,7 @@ you will be able to write your own analyzers.
 - [x] serviceAnalyzer
 - [x] eventAnalyzer
 - [x] ingressAnalyzer
+- [x] statefulSetAnalyzer
 
 #### Optional
 
@@ -254,4 +255,4 @@ Find us on [Slack](https://k8sgpt.slack.com/)
 
 <a href="https://github.com/k8sgpt-ai/k8sgpt/graphs/contributors">
   <img src="https://contrib.rocks/image?repo=k8sgpt-ai/k8sgpt" />
-</a>
+</a>