readme: list of parser libraries

README.md

@@ -102,6 +102,20 @@ The syntax is pretty fast-forward, it uses 3 levels to find your configuration l
 
 
 
+#### File Formats
+
+Configuration files can be written according to some standards or application-specific syntax. This tool uses standard and third-party to parse the following formats :
+
+- [xml](https://fr.wikipedia.org/wiki/Extensible_Markup_Language) and [json](https://json.org/) are read/written using the go standard library (_cf. [json](https://golang.org/pkg/encoding/json/), [xml](https://golang.org/pkg/encoding/xml/)_).
+- [yaml](https://en.wikipedia.org/wiki/YAML) with [go-yaml/yaml](https://github.com/go-yaml/yaml).
+
+-  [ini](https://en.wikipedia.org/wiki/INI_file) with [go-ini/ini](https://github.com/go-ini/ini).
+-  [toml](https://en.wikipedia.org/wiki/TOML) with [BurntSushi/toml](https://github.com/BurntSushi/toml).
+-  [nginx configurations](https://docs.nginx.com/nginx/admin-guide/basic-functionality/managing-configuration-files/) with [lytics/confl](https://github.com/lytics/confl).
+-  _and more to come..._
+
+
+
 ----
 
 ## Example