docs: tweak Count API docs (#1522)

Author: dconeybe

google-cloud-firestore/src/main/java/com/google/cloud/firestore/Query.java

@@ -1923,9 +1923,8 @@ boolean shouldRetryQuery(
    * <em>without actually downloading the documents</em>.
    *
    * <p>Using the returned query to count the documents is efficient because only the final count,
-   * not the documents' data, is downloaded. The returned query can even count the documents if the
-   * result set would be prohibitively large to download entirely (for example thousands of
-   * documents).
+   * not the documents' data, is downloaded. The returned query can count the documents in cases
+   * where the result set is prohibitively large to download entirely (thousands of documents).
    *
    * @return a query that counts the documents in the result set of this query.
    */
@@ -1935,13 +1934,13 @@ public AggregateQuery count() {
   }
 
   /**
-   * Calculates the specified aggregations over the documents in the result set of the given query,
-   * without actually downloading the documents.
+   * Calculates the specified aggregations over the documents in the result set of the given query
+   * <em>without actually downloading the documents</em>.
    *
-   * <p>Using this function to perform aggregations is efficient because only the final aggregation
-   * values, not the documents' data, is downloaded. This function can even perform aggregations of
-   * the documents if the result set would be prohibitively large to download entirely (for example
-   * thousands of documents).
+   * <p>Using the returned query to perform aggregations is efficient because only the final
+   * aggregation values, not the documents' data, is downloaded. The returned query can perform
+   * aggregations of the documents in cases where the result set is prohibitively large to download
+   * entirely (thousands of documents).
    *
    * @return an {@link AggregateQuery} that performs aggregations on the documents in the result set
    *     of this query.