Add basic contributing instructions

Signed-off-by: Taylor Smock <[email protected]>

README.md

@@ -5,6 +5,17 @@ This repository contains formatter URLs for OpenStreetMap keys. The data is obta
 - Wikidata items which have [OSM tag or key (P1282)](https://www.wikidata.org/wiki/Property:P1282) and [formatter URL (P1630)](https://www.wikidata.org/wiki/Property:P1630) defined
 - OSM Wiki Wikibase via the OSM Sophox Service which have [formatter URL (P8)](https://wiki.openstreetmap.org/wiki/Property:P8)
 
+## Contributing
+### OSM Wiki Data
+1. Read [https://wiki.openstreetmap.org/wiki/Data\_items](https://wiki.openstreetmap.org/wiki/Data_items).
+2. Create the item (see [https://wiki.openstreetmap.org/wiki/Data\_items#Item\_creation\_process](https://wiki.openstreetmap.org/wiki/Data_items#Item_creation_process)).
+3. Input the standard information for the tag. Be as complete as possible please. Other software may use this information (such as for validation purposes).
+4. Add the `formatter url` (`P8`) property.
+5. Don't forget to add the [site link](https://wiki.openstreetmap.org/wiki/Special:SetSiteLink) (see #2 for details).
+6. Wait for the next update
+
+Example: [https://wiki.openstreetmap.org/wiki/Item:Q401](https://wiki.openstreetmap.org/wiki/Item:Q401)
+
 ## Usage
 
 Use `index.json` in your application. Replace `$1` with the tag value.