Document the mifare_tag_type enum.

HACKING

@@ -37,6 +37,8 @@ infrastructure ready for hacking the new card support:
   - Edit libfreefare/freefare.h:
       - Add your tag to the `mifare_tag_type' enum;
       - Add a <tag>_connect() and a <tag>_disconnect() function prototype;
+  - Edit libfreefare/freefare.3:
+      - Add your tag to the `mifare_tag_type' enum documentation;
   - Edit libfreefare/freefare_internal.h:
       - Add a new <tag>_tag struct.  It's very first member shall be `struct
 	mifare_tag __tag';

libfreefare/freefare.3

@@ -50,6 +50,13 @@ Mifare card manipulation library (libfreefare, \-lfreefare)
 .In freefare.h
 .Ft "MifareTag *"
 .Fn freefare_get_tags "nfc_device_t *device"
+.Bd -literal
+enum mifare_tag_type {
+    ULTRALIGHT,
+    CLASSIC_1K,
+    CLASSIC_4K
+};
+.Ed
 .Ft enum mifare_tag_type
 .Fn freefare_get_tag_type "MifareTag tag"
 .Ft "const char *"