Updating Contribution.md and fixxed error in repo file

Contributing.md

@@ -23,6 +23,8 @@ The institution blocks look like this:
 
 **Generate V4 UUID:** https://www.uuidgenerator.net/version4
 
+**Important:** oid as seen in [github_repos.json](/github_repos.json) will be created automaticly when updating the Database, so it doesn't need to be added by you.
+
 **Important:**
 sector needs to be one of these:
 - FoodBeverage
@@ -44,3 +46,11 @@ sector needs to be one of these:
 Just edit or append a new block to the file and make a pull request.
 
 If everything is correct it will be added and updated on the website.
+
+### What are ts and why are they set to null
+
+ts are timestamps that are used to check when that organization/institution were crawled.
+
+"null" is the intial value so that the new organization/institution will be crawled with the next crawl run.
+
+After that it will be overwritte in the database.

github_repos.json

@@ -450,7 +450,7 @@
   "shortname": "friendly",
   "name_de": "Friendly",
   "orgs": [
-    { "name": "friendlydotch", "ts": null },
+    { "name": "friendlydotch", "ts": null }
   ]
 },
 {