typo fix

change "ids" to "IDs"

Author: American-Dipper

articles/cosmos-db/index-overview.md

@@ -30,7 +30,7 @@ Azure Cosmos database applies *automatic indexing* to the data, where every path
 
 Azure Cosmos database employs inverted index data structure to store the information of each item and to facilitate efficient representation for querying. The index tree is a document that is constructed with the union of all of the trees representing the individual items in a container. The index tree grows over time, as new items are added or existing items are updated in the container. Unlike relational database indexing, Azure Cosmos DB doesn't restart the indexing from scratch, as new fields are introduced. New items are added to the existing index structure. 
 
-Each node of the index tree is an index entry containing the label and position values, called the *term*, and the ids of the items, called the *postings*. The postings in the curly brackets (for example {1,2}) in the inverted index figure correspond to the items such as *Document1* and *Document2* containing the given label value. An important implication of treating both the schema labels and the instance values uniformly is that everything is packed inside a large index. An instance value that is still in the leaves is not repeated, it can be in different roles across items, with different schema labels, but it is the same value. The following image shows inverted indexing for two different items:
+Each node of the index tree is an index entry containing the label and position values, called the *term*, and the IDs of the items, called the *postings*. The postings in the curly brackets (for example {1,2}) in the inverted index figure correspond to the items such as *Document1* and *Document2* containing the given label value. An important implication of treating both the schema labels and the instance values uniformly is that everything is packed inside a large index. An instance value that is still in the leaves is not repeated, it can be in different roles across items, with different schema labels, but it is the same value. The following image shows inverted indexing for two different items:
 
 ![Indexing under the hood, inverted Index](./media/index-overview/inverted-index.png)