Concepts and Terminology setup

In this issue, we write the specifications of how the topic 'Concepts and Terminology' is/will be organized. This top message contains such specifications, and will be edited/updated as needed and agreed. Subsequent messages document the discussions.

1. There will be a directory docs/terminology, that will contain all terminology-related documents that are authored or otherwise contributed to the 'body of terminology'. This includes images, pattern descriptions, term descriptions.
2. Contributed images must be stored in docs/terminology/images.
3. Contributed pattern descriptions must be stored in docs/terminology/patterns. The filename must start with 'pattern-', and must not contain spaces.
4. Contributed term descriptions must be stored in in docs/terminology/terms. The filename must start with 'term-', and must not contain spaces.

#11 (closed) specifies how artifacts such as an eSSIF-Lab Glossary, term-pages and pattern-pages are being generated from these source files.