Update README.md

README.md

-FrechCropUsage is a thesaurus of crop organized by usage. 
+FrenchCropUsage is a thesaurus of crop organized by usage. 
 This thesaurus is dedicated to french agriculture point of view.
+The file called usageCulture20160531.rdf is the version of mai 2016. 
+The thesaurus is modelled using skos. It contains 307 skos:Concept individuals.
+
+The thesaurus was first used during the vespa project to index 
+French agricultural alert  bulletins named "Plant Health Bulletins" or 
+"Bulletins de Santé du Végétal" (BSV).
+
+This thesaurus is also used during the D2KAB project to index a new version 
+of the BSV corpora.