Align the structure of datatype MD files

[chenejac]

For datatypes with components (xsd:complexType)

1. Definition: The scope of the datatype and its meaning.
2. Notes: An additional description to communicate the purpose of the datatype.
3. Specialization of: The link to the super datatype (the datatype this type extends)
4. Components: The list of fields the datatype is composed of. Similar to attributes for entities.
5. Restrictions: An enumerated list of restrictions that apply between components (e.g. The start date and end date must have the same granularity)

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6. Matches: Describe any external datatypes this datatype matches.
7. References: References to external resources in case these are referenced.

For datatypes without components (xsd:simpleType)

1. Definition: The scope of the datatype and its meaning.
2. Notes: An additional description to communicate the purpose of the datatype.
3. Based on: The link to the base datatype (the datatype this type restricts)
4. Restrictions: An enumerated list of restrictions that apply (e.g. maximum length, regular expression, possibly also algorithmic restrictions such as checksums)
5. Examples: A list of examples

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6. Matches: Describe any external datatypes this datatype matches.
7. References: References to external resources in case these are referenced.