Timelion deprecated (#2045)

This PR adds a long overdue deprecated flag to the Timelion docs, and
updates the initial steps for creating the visualization and adding it
to a dashboard

Closes: #1962

I'll create an equivalent in asciidoc for previous versions

Author: florent-leborgne

explore-analyze/visualize/legacy-editors/timelion.md

@@ -1,7 +1,7 @@
 ---
 applies_to:
-  stack: ga
-  serverless: ga
+  stack: deprecated 7.10
+  serverless: unavailable
 ---
 
 # Timelion [timelion]
@@ -84,19 +84,15 @@ Set up Metricbeat, then create the dashboard.
 2. Go to **Dashboards**.
 3. On the **Dashboards** page, click **Create dashboard**.
 
+You can only add Timelion visualizations to a dashboard if they're already saved in the **Visualize Library**, using the **Add from library** option.
 
-## Open and set up Timelion [_open_and_set_up_timelion]
+## Create a Timelion visualization [_open_and_set_up_timelion]
 
-Open **Timelion** and change the time range.
-
-1. On the dashboard, click **All types > Aggregation based**, then select **Timelion**.
-2. Make sure the [time filter](../../query-filter/filtering.md) is **Last 7 days**.
-
-
-## Create a time series visualization [timelion-tutorial-create-time-series-visualizations]
-
-To compare the real-time percentage of CPU time spent in user space to the results offset by one hour, create a time series visualization.
+$$$timelion-tutorial-create-time-series-visualizations$$$
 
+1. Go to the **Visualize Library** and select **Create visualization**.
+2. In the **Legacy** tab, select **Aggregation-based**, then **Timelion**.
+3. Make sure the [time filter](../../query-filter/filtering.md) is **Last 7 days**.
 
 ### Define the functions [define-the-functions]