* Change center layout strategy to allow vertical anchoring
Affects `telescope.pickers.layout_strategies.center` that is used by dropdown
(`telescope.themes.get_dropdown()`) theme, allowing more customization for
dropdown theme, i. e. setting it in the top with mirrored preview.
For `anchor` containing `N` or `S` will ignore `mirror` config
and preview will be placed as follows:
- Anchoring for `N` put the preview below the prompt result block.
- Anchoring for `S` put the preview above the prompt result block.
- For horizontal anchoring preview will be placed according to `mirror`.
* [docgen] Update doc/telescope.txt
skip-checks: true
Co-authored-by: Github Actions <actions@github>