Update foodon.md (#2609)

* Update foodon.md

* Added links to example pages containing FoodOn IDs

* Add description to usage examples

* Dropped PTFI DB example because of login

* removed non pubmed publication reference

---------

Co-authored-by: Deepak <deepakunni3@users.noreply.github.com>

Author: ddooley

ontology/foodon.md

@@ -20,8 +20,8 @@ description: A broadly scoped ontology representing entities which bear a “foo
 domain: diet, metabolomics, and nutrition
 homepage: https://foodon.org/
 license:
-  label: CC BY 3.0
-  url: http://creativecommons.org/licenses/by/3.0/
+  label: CC BY 4.0
+  url: http://creativecommons.org/licenses/by/4.0/
 preferredPrefix: FOODON
 products:
 - id: foodon.owl
@@ -37,6 +37,22 @@ repository: https://github.com/FoodOntology/foodon
 tags:
 - food
 tracker: https://github.com/FoodOntology/foodon/issues/
+usages:
+- description: FoodData Central nutrition database web portal provided by USDA Agricultural Research Service.
+  examples:
+  - description: An entry for 'Apples, fuji, with skin, raw' from the FoodData Central nutrition database which is annotated with the term FOODON:00002862.
+    url: https://fdc.nal.usda.gov/fdc-app.html#/food-details/1750340/attributes
+  user: https://fdc.nal.usda.gov/
+- description: FDA GenomeTrackr surveillance program for reporting foodborne pathogen biosamples.
+  examples:
+  - description: An entry from NCBI Biosample that describes a *Samonella enterica* sample extracted from Chicken and annotated with the term FOODON:03411457.
+    url: https://www.ncbi.nlm.nih.gov/biosample/SAMN03455272
+  user: https://www.fda.gov/food/whole-genome-sequencing-wgs-program/genometrakr-network
+- description: Wiki database consolidating over 30 global food composition databases.
+  examples:
+  - description: An entry from WikiFCD that describes Walnuts and is annotated with the term FOODON:03301364.
+    url: https://wikifcd.wikibase.cloud/wiki/Item:Q568877
+  user: https://wikifcd.wikibase.cloud/wiki/Main_Page
 activity_status: active
 ---