Add PHP library link

Author: otar

index.markdown

@@ -102,6 +102,9 @@ Here is a non-exhaustive list:
 **Python**
 - [n-takumasa/json-with-comments](https://github.com/n-takumasa/json-with-comments)
 
+**PHP**
+- [otar/jsonc](https://github.com/otar/jsonc)
+
 **Rust**
 - [dprint/jsonc-parser](https://github.com/dprint/jsonc-parser)
 
@@ -130,4 +133,4 @@ At the time of writing this document, the "JSON with Comments" mode still accept
 
 ### [RFC2119]
 
-Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.
+Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.