Add proposed definition of the GEDZIP media type

Since it was decided that the GEDZIP version and gedcom.ged file version
must match, then the version parameter in the media type can be used to
specify how to interpret the GEDZIP format.

But since .gdz files come without a media type, we still need to specify
how to interpret a .gdz file when you don't know if it's 7.0 or some
future version.

Fixes #5

Signed-off-by: Dave Thaler <dthaler@armidalesoftware.com>

version-detection/version-detection.md

@@ -114,6 +114,8 @@ Byte sequence  | Explanation | Reference
 
 ## IANA Media Type Registration
 
+### text/vnd.familysearch.gedcom
+
 This section defines the "text/vnd.familysearch.gedcom" media type for use with protocols such as HTTP or email, to identify content
 as being a GEDCOM file.  The Internet Assigned Numbers Authority (IANA) maintains the
 [registry of assigned media types](https://www.iana.org/assignments/media-types/media-types.xhtml).
@@ -180,3 +182,58 @@ one-place and one-name studies, and historical analysis of interrelated individu
 **Intended Use**: Common
 
 Used for exchanging and storage of computerized genealogical data. Primary use is for inter-operable software products to assist genealogists, historians, and other researchers. Secondary use is as a long-term storage format for preserving genealogical information.
+
+### application/vnd.familysearch.gedcom+zip
+
+This section defines the "application/vnd.familysearch.gedcom+zip" media type for use with protocols such as HTTP or email, to identify content
+as being a GEDZIP file.  The Internet Assigned Numbers Authority (IANA) maintains the
+[registry of assigned media types](https://www.iana.org/assignments/media-types/media-types.xhtml).
+
+The following registration for "application/vnd.familysearch.gedcom+zip" is specified using the template defined in
+[RFC 4288](https://www.rfc-editor.org/rfc/rfc4288).
+
+**Name**: application/vnd.familysearch.gedcom+zip
+
+**Parameters**:
+
+* **version**: The version of the GEDCOM specification that specifies the GEDZIP format.
+  The GEDCOM version of the gedcom.ged file within the archive must match the GEDZIP version number,
+  and since the GEDZIP format was just added in FamilySearch GEDCOM 7.0, inclusion of the version
+  parameter is optional, as absense implies version 7.0.
+
+**Encoding considerations**: See the specification for considerations about the GEDZIP archive format.
+
+**Security considerations**:
+A GEDZIP archive payload can contain one or more files, including a GEDCOM file, and any other files it references.
+Such files may include personal and sensitive information as well as information commonly used to create
+security questions. This information is not encrypted or otherwise
+protected by GEDCOM or the ZIP archive itself; hence, it falls on the software and persons managing the files to ensure they are
+kept confidential if they contain such information.  Similarly, as with other types of archive formats,
+the archive might contain executable code or scripts, and it falls on the software and persons managing
+the files to guard against malicious files.
+
+**Interoperability considerations**: The GEDCOM version is encoded in the gedcom.ged file in the archive,
+and an algorithm is provided for detecting the version.
+
+**Application usage**: GEDCOM is used by family history and related applications, including family trees,
+one-place and one-name studies, and historical analysis of interrelated individuals.
+
+**Fragment Identifier**: not used
+
+**Restrictions on Use**: none
+
+**Provisional Registration**: This media type is intended to be permanent.
+
+**Magic numbers**: none
+
+**File Extension**: .gdz
+
+**Mac OS File Type Code**: none
+
+**Intended Use**: Common
+
+Used for exchanging and storage of computerized genealogical data. The primary use is for interoperable
+software products to assist genealogists, historians, and other researchers. The secondary use is as a
+long-term storage format for preserving genealogical information.
+
+**Specification**: https://gedcom.io/specifications/FamilySearchGEDCOMv7.pdf section 4