feat(lua): allow passing handles to vim.b/w/t

vim.bo can target a specific buffer by indexing with a number, e.g:
`vim.bo[2].filetype` can get/set the filetype for buffer 2. This change
replicates that behaviour for the variable namespace.

1 files changed, 7 insertions, 3 deletions

diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index a6ccf9f35c..f8576a05fe 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -928,6 +928,7 @@ Example: >
     vim.g.foo = 5     -- Set the g:foo Vimscript variable.
     print(vim.g.foo)  -- Get and print the g:foo Vimscript variable.
     vim.g.foo = nil   -- Delete (:unlet) the Vimscript variable.
+    vim.b[2].foo = 6  -- Set b:foo for buffer 2
 
 vim.g                                                   *vim.g*
         Global (|g:|) editor variables.
@@ -935,15 +936,18 @@ vim.g                                                   *vim.g*
 
 vim.b                                                   *vim.b*
         Buffer-scoped (|b:|) variables for the current buffer.
-        Invalid or unset key returns `nil`.
+        Invalid or unset key returns `nil`. Can be indexed with
+        an integer to access variables for a specific buffer.
 
 vim.w                                                   *vim.w*
         Window-scoped (|w:|) variables for the current window.
-        Invalid or unset key returns `nil`.
+        Invalid or unset key returns `nil`. Can be indexed with
+        an integer to access variables for a specific window.
 
 vim.t                                                   *vim.t*
         Tabpage-scoped (|t:|) variables for the current tabpage.
-        Invalid or unset key returns `nil`.
+        Invalid or unset key returns `nil`. Can be indexed with
+        an integer to access variables for a specific tabpage.
 
 vim.v                                                   *vim.v*
         |v:| variables.