docs: detail indexing, slicing, and length checking

Author: jorwoods

docs/filter-sort.md

@@ -138,6 +138,21 @@ Sort can take multiple args, with desc direction added as a (-) prefix
 workbooks = workbooks.order_by("project_name", "-created_at")
 ```
 
+### Indexing and slicing
+
+Querysets can be indexed and sliced like a list. The query is executed at when
+the queryset is indexed or sliced.
+```py
+# Get the first item in the queryset
+flow = server.flows.filter(owner_name="admin")[0]
+
+# Get the last item in the queryset
+flow = server.flows.filter(owner_name="admin")[-1]
+
+# Get the most recent 10 runs from a flow
+runs = server.flow_runs.filter(flow_id=flow.id, page_size=10).order_by("-created_at")[:10]
+```
+
 ### Supported endpoints
 
 The following endpoints support the Django style filters and sorts:
@@ -174,10 +189,7 @@ views = server.views.filter(project_name=project_name, tags="stale")
 # sort can take multiple args, with desc direction added as a (-) prefix 
 workbooks = workbooks.order_by("project_name", "-created_at")
 
-# pagination take these two keywords
-workbooks = workbooks.paginate(page_size=10, page_number=2) 
-
-# query is executed at time of access
+# query is executed at time of iteration
 for workbook in workbooks: 
     print(workbook)
 
@@ -189,6 +201,11 @@ all_workbooks = server.workbooks.filter(project_name=project_name).order_by("-pr
 
 # operators are implemented using dunderscore
 all_workbooks = server.workbooks.filter(project_name__in=["Project A", "Project B"])
+
+# How many items are in the queryset?
+flows = server.flows.filter(owner_name="admin")
+print(len(flows))
+
 ```
 
 ### Operators available