doc: clarify window-id, tab-id, nvim_set_current_x #32528

Problem:
Descriptions are somewhat vague. nvim_set_current_line modifies contents
but nvim_set_current_buf does not, etc.

Solution:
- Make it clear that these functions accept or return a winid/tabid by
  linking to that concept in help.
- Only these few files use the term "handles", so replace them with the
  more conventional terminology.
- Add a new help section for tab-ID. This concept is unique to neovim
  because vim exposes tabnr, but not tab handles. This section is
  modelled after `:h winid`.

runtime/lua/vim/treesitter.lua

@@ -306,7 +306,7 @@ end
 
 --- Returns a list of highlight capture names under the cursor
 ---
----@param winnr (integer|nil) Window handle or 0 for current window (default)
+---@param winnr (integer|nil): |window-ID| or 0 for current window (default)
 ---
 ---@return string[] List of capture names
 function M.get_captures_at_cursor(winnr)