lib: Kconfig: enhance help for ASN1

Enhance the help for configs ASN1_COMPILER
and ASN1_decoder.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/lib/Kconfig b/lib/Kconfig
index 3c6fa99..b0e5d60 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -791,11 +791,23 @@
 
 config ASN1_COMPILER
 	bool
+	help
+	  ASN.1 (Abstract Syntax Notation One) is a standard interface
+	  description language for defining data structures that can be
+	  serialized and deserialized in a cross-platform way. It is
+	  broadly used in telecommunications and computer networking,
+	  and especially in cryptography (https://en.wikipedia.org/wiki/ASN.1).
+	  This option enables the support of the asn1 compiler.
 
 config ASN1_DECODER
 	bool
 	help
-	  Enable asn1 decoder library.
+	  ASN.1 (Abstract Syntax Notation One) is a standard interface
+	  description language for defining data structures that can be
+	  serialized and deserialized in a cross-platform way. It is
+	  broadly used in telecommunications and computer networking,
+	  and especially in cryptography (https://en.wikipedia.org/wiki/ASN.1).
+	  This option enables the support of the asn1 decoder.
 
 config OID_REGISTRY
 	bool