Vim insert current time

I'm using Jekyll, and Jekyll's post needed a date time for metadata like below, it would be better if we have a shorthand for date time insertion.

---
layout: post  
title:  "pandemic"  
date:   2021-11-17 19:19:26 +0800  
---

in my .vimrc

...

" insert current date time
" e.g. 2021-11-17 19:19:26 +0800
nnoremap <F5> "=strftime("%Y-%m-%d %H:%M:%S %z")<CR>P  
inoremap <F5> <C-R>=strftime("%Y-%m-%d %H:%M:%S %z")<CR>

...

Since Vim already had a build-in function strftime so it can be done very easily.

Now on Vim editor, I can insert date time by F5.