feat(builtin.buffers): enhance and bind delete_buffer action (#3145)

* feat(builtin.buffers): enhance and bind `delete_buffer` action

* change default bind and add docs

* [docgen] Update doc/telescope.txt
skip-checks: true

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Co-authored-by: Github Actions <actions@github>

doc/telescope.txt

@@ -1434,6 +1434,8 @@ builtin.reloader({opts})                        *telescope.builtin.reloader()*
 builtin.buffers({opts})                          *telescope.builtin.buffers()*
     Lists open buffers in current neovim instance, opens selected buffer on
     `<cr>`
+    - Default keymaps:
+      - `<M-d>`: delete the currently selected buffer
 
 
     Parameters: ~