doc(layout_strategies): document shared options for bottom_pane (#2887)

* doc(layout_strategies): document shared options for `bottom_pane`

* [docgen] Update doc/telescope.txt
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Co-authored-by: Github Actions <actions@github>

doc/telescope.txt

@@ -2357,6 +2357,21 @@ layout_strategies.bottom_pane()               *telescope.layout.bottom_pane()*
 
     For an easy ivy configuration, see |themes.get_ivy()|
 
+    `picker.layout_config` shared options:
+      - height:
+        - How tall to make Telescope's entire layout
+        - See |resolver.resolve_height()|
+      - mirror: Flip the location of the results/prompt and preview windows
+      - prompt_position:
+        - Where to place prompt window.
+        - Available Values: 'bottom', 'top'
+      - scroll_speed: The number of lines to scroll through the previewer
+
+    `picker.layout_config` unique options:
+      - preview_cutoff: When columns are less than this value, the preview will be disabled
+      - preview_width:
+        - Change the width of Telescope's preview window
+        - See |resolver.resolve_width()|