added list of prefixes used in diagrams

![Property diagram](/documentation/diagrams/Property.png)

### State

![State diagram](/documentation/diagrams/State.png)

### Legend for diagrams

![Legend for diagrams](/documentation/diagrams/overview_legend.png)

### Symbology legend for diagrams

![Symbology legend for diagrams](/documentation/diagrams/overview_legend.png)

### Prefixes used in diagrams

```

@prefix geo: <http://www.opengis.net/ont/geosparql#> .

@prefix org: <https://www.w3.org/ns/org#> .

@prefix owl: <http://www.w3.org/2002/07/owl#> .

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

@prefix foaf: <http://xmlns.com/foaf/0.1/> .

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

@prefix time: <http://www.w3.org/2006/time#> .

@prefix saref: <https://saref.etsi.org/core/> .

@prefix s4auto: <https://saref.etsi.org/saref4auto/> .

@prefix s4mari: <https://saref.etsi.org/saref4mari/> .

@prefix s4syst: <https://saref.etsi.org/saref4syst/> .

```