Update classifier.md

Author: fordprefect480

articles/ai-services/content-understanding/concepts/classifier.md

@@ -44,7 +44,7 @@ Content Understanding classifier can analyze a single- or multi-file documents t
 
 ### How to use Content Understanding classifier
 
-Content Understanding classifier doesn't require any training dataset. Define up to 50 category name and description and create a classifier. By default, the entire file is treated as a single content object, meaning the file/object is associated to a single category.
+A Content Understanding classifier doesn't require any training dataset. Define up to 50 category name and description and create a classifier. By default, the entire file is treated as a single content object, meaning the file/object is associated to a single category.
 
 However, when you have more than one document in a file, the classifier can identify the different document types contained within the input file with splitting capability. The classifier response contains the page ranges for each of the identified document types contained within a file. This response can include multiple instances of the same document type.