update note about vim.cmd

closes #61

README.md

@@ -433,10 +433,19 @@ vim.api.nvim_command('set nonumber')
 vim.api.nvim_command('%s/foo/bar/g')
 ```
 
-Note: `vim.cmd` is a shorter alias for this function
+### vim.cmd()
+
+Alias for `vim.api.nvim_exec()`. Only the command argument is needed, `output` is always set to `false`.
 
 ```lua
 vim.cmd('buffers')
+vim.cmd([[
+let g:multiline =<< EOF
+foo
+bar
+baz
+EOF
+]])
 ```
 
 #### Tips

doc/nvim-lua-guide.txt

@@ -543,10 +543,20 @@ the command to execute.
     vim.api.nvim_command('%s/foo/bar/g')
 <
 
-Note: `vim.cmd` is a shorter alias for this function
+vim.cmd()~
+
+Alias for `vim.api.nvim_exec()`. Only the command argument is needed,
+`output` is always set to `false`.
 
     >
     vim.cmd('buffers')
+    vim.cmd([[
+    let g:multiline =<< EOF
+    foo
+    bar
+    baz
+    EOF
+    ]])
 <
 
 Tips~