doc: Forgot make doc

doc/formats.md

@@ -111,15 +111,17 @@ fq -d raw 'mp4({force: true})' file.mp4
 
 ### asn1_ber
 
-Can also decode CER and BER but with no extra validation. Currently does not support specifying a schema.
+Supports decoding BER, CER and DER ([X.690]([X.690_1297.pdf)).
 
-Supports `torepr` but without schema support it's not that useful:
+- Currently no extra validation is done for CER and DER.
+- Does not support specifying a schema.
+- Supports `torepr` but without schema all sequences and sets will be arrays.
 
 ```
 fq -d asn1_ber torepr file.ber
 ```
 
-There is also `frompem` and `topem` to help working with PEM format:
+Functions `frompem` and `topem` can help working with PEM format:
 
 ```
 fq -d raw 'frompem | asn1_ber | d' cert.pem
@@ -130,6 +132,19 @@ If the schema is known and not that complicated it can be reproduced:
 ```
 fq -d asn1_ber 'torepr as $r | ["version", "modulus", "private_exponent", "private_exponen", "prime1", "prime2", "exponent1", "exponent2", "coefficient"] | with_entries({key: .value, value: $r[.key]})' pkcs1.der
 ```
+
+Can be used to decode nested parts:
+
+```
+fq -d asn1_ber '.constructed[1].value | asn1_ber' file.ber
+```
+
+References and tools:
+- https://www.itu.int/ITU-T/studygroups/com10/languages/X.690_1297.pdf
+- https://en.wikipedia.org/wiki/X.690
+- https://letsencrypt.org/docs/a-warm-welcome-to-asn1-and-der/
+- https://lapo.it/asn1js/
+
 ### avro_ocf
 
 Supports reading Avro Object Container Format (OCF) files based on the [1.11.0 specification](https://avro.apache.org/docs/current/spec.html#Object+Container+Files).