updating the readme

README.md

@@ -187,6 +187,8 @@ Specify the output as a lowercase input to the flag:
 replay-zero --template=gatling
 ```
 
+#### Custom templates
+
 You can also pass path to your own custom template (in case you dont want to use karate or gatling) to the same paramater and `--extension` or `-e` to pass extentsion of the output.
 
 E.g.
@@ -195,6 +197,9 @@ E.g.
 replay-zero --template=/path/to/your/custom-template --extension=java
 ```
 
+Templates are following the format from the [text/template](https://golang.org/pkg/text/template/) package. And it also support all template functions provided by [Sprig](http://masterminds.github.io/sprig/). You can even extend your template's functionality with string manipulation, math operators, and more from the Sprig library
+
+
 ## Roadmap
 
 Replay Zero has many plans for improvement which you can find in the Issues tab of this repo. Now that you've read the entire README up until this point (right?) and know of all the features Replay Zero offers, here is a visual recap of both some of the features currently provided (multiple target proxying, output templating) as well as some planned roadmap items (remote proxyingm, custom template sourcing) and how they may fit in alongside existing features.