minor: add NoMaxAge sign option helper

Author: kataras

claims.go

@@ -245,7 +245,10 @@ func MaxAge(maxAge time.Duration) SignOptionFunc {
 }
 
 // NoMaxAge is a SignOption to set the expiration "exp", "iat" JWT standard claims to zero.
-func NoMaxAge(c *Claims) {
+//
+// Usage:
+// Sign(alg, key, claims, NoMaxAge)
+var NoMaxAge SignOptionFunc = func(c *Claims) {
 	c.Expiry = 0
 	c.IssuedAt = 0
 }

sign.go

@@ -84,6 +84,8 @@ func signToken(alg Alg, key PrivateKey, encrypt InjectFunc, claims any, customHe
 //
 // Available SignOptions:
 // - MaxAge(time.Duration)
+// - NoMaxAge()
+// - []Audience{"aud"}
 // - Claims{}
 type SignOption interface {
 	// ApplyClaims should apply standard claims.