feat(picker): allow appending original window cword to prompt (#2878)

* feat(picker): allow appending original window cword to prompt

* add default mapping and document

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

* add mapping to README

also format README

* oops

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

---------

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

lua/telescope/actions/init.lua

@@ -1484,6 +1484,13 @@ actions.delete_mark = function(prompt_bufnr)
   end)
 end
 
+--- Insert the word under the cursor of the original (pre-Telescope) window
+---@param prompt_bufnr number: The prompt bufnr
+actions.insert_original_cword = function(prompt_bufnr)
+  local current_picker = action_state.get_current_picker(prompt_bufnr)
+  current_picker:set_prompt(current_picker.original_cword, false)
+end
+
 actions.nop = function(_) end
 
 -- ==================================================