docs: update dashboard throughput docs (#9799)

Author: shereezhang

docs/source/guide/dashboard_throughput.md

@@ -35,10 +35,10 @@ The top of the dashboard shows summary cards for the selected date range.
 
 | KPI | Description |
 |-----|-------------|
-| **Tasks Done** | Number of tasks that reached the [Done state](project_states#Task-states) during the selected date range. |
-| **Avg Tasks Done / Day** | Average number of tasks completed per day in the selected date range. Calculated as Tasks Done / Days.|
-| **Total Time Spent** | Total time spent annotating and reviewing. Note: Annotation time uses active annotation time, as opposed to [lead time](dashboard_annotator#Annotations).
-| **Avg Time / Task** | Average time spent per Done task. Calculated as Total Time Spent / Tasks Done.|
+| **Tasks Done** | Number of tasks that reached the [Done state](project_states#Task-states) during the selected date range.<br /><br /> **Avg Tasks Done / Day** sub-metric shows the average number of tasks completed per day in the selected date range. Calculated as Tasks Done / Days.   |
+| **Annotations Submitted** | Total number of annotations submitted (manually or created from a prediction) during the selected date range. <br /><br /> **Annotations / Day** sub-metric shows the average number of annotations submitted per day in the selected date range. Calculated as Annotations Submitted / Days.|
+| **Total Time Spent** | Total time spent annotating and reviewing. Note: Annotation time uses active annotation time, as opposed to [lead time](dashboard_annotator#Annotations).<br /><br /> The sub-metric shows the Total Time Spent on Done Tasks.
+| **Avg Time / Task** | Average active time spent per task that has started work (ie. past the initial stage). Calculated as Total Time Spent / Tasks Started. <br /><br /> The sub-metric shows the Total Time Spent on Done Tasks / Tasks Done. |
 
 !!! note
     Task state metrics are based on [project and task state management](project_states). If state tracking was enabled after some project work had already happened, earlier state transitions might not appear in the dashboard.
@@ -47,6 +47,6 @@ The top of the dashboard shows summary cards for the selected date range.
 
 | Chart | Description |
 |-------|-------------|
-| **Remaining Tasks by State** | Stacked bar chart of tasks remaining in each state over time. A shrinking chart indicates work is progressing; a growing segment in one state suggests a bottleneck; a high number in review states suggests reviewers are not keeping pace with annotators. |
+| **Tasks by State** | Stacked bar chart of the number of tasks in each state (Initial, Annotating, Needs Review, In Review, Done) over time. Use it to track task progress or identify bottlenecks.<br /><br /> Tasks start at the **Initial** state when they have been created but contain no annotations yet. Tasks that have completed the required number of annotations either move to the **Needs Review** or **Done** state, depending on whether your project settings require a review on the task. [Learn more about task state management](project_states#Task-states).|
 | **Tasks Done / Day** | Number of tasks reaching the Done state per day. The same task may appear on multiple days if it is re-worked after reaching Done. Use it to track velocity and spot output changes after adjusting staffing, task instructions, review requirements, or project settings. |
 | **Time Spent** | Time spent over the selected period, split between annotation and review. Use it to understand how effort is distributed across work types over time. |