add pricing info for rerank models

Author: msakande

articles/ai-studio/how-to/deploy-models-cohere-rerank.md

@@ -30,6 +30,10 @@ Cohere offers rerank models in [Azure AI Foundry](https://ai.azure.com). These m
 
 You can browse the Cohere family of models in the [Model Catalog](model-catalog.md) by filtering on the Cohere collection.
 
+#### Pricing for Cohere Rerank models
+
+*Queries*, not to be confused with a user's query, is a pricing meter that refers to the cost associated with the tokens used as input for inference of a Cohere Rerank model. Cohere counts a single search unit as a query with up to 100 documents to be ranked. Documents longer than 4096 tokens when including the length of the search query are split up into multiple chunks, where each chunk counts as a single document.
+
 # [Cohere Rerank v3.5](#tab/cohere-rerank-3-5)
 
 Cohere Rerank 3.5 provides a significant boost to the relevancy of search results. This AI model, also known as a cross-encoder, precisely sorts lists of documents according to their semantic similarity to a provided query. This action allows information retrieval systems to go beyond keyword search, and also outperform traditional embedding models, surfacing the most contextually relevant data within end-user applications.