Update README.md - fix node20 name (previously node18)

Signed-off-by: João Paulo Séder <jpfmscel@gmail.com>

README.md

@@ -18,7 +18,7 @@ This repository contains the Classic OpenFaaS templates, but many more are avail
 | node16 | NodeJS | 16 | Alpine Linux | of-watchdog | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/node16)
 | node17 | NodeJS | 17 | Alpine Linux | of-watchdog | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/node17)
 | node18 | NodeJS | 18 | Alpine Linux | of-watchdog | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/node18)
-| node18 | NodeJS | 20 | Alpine Linux | of-watchdog | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/node20)
+| node20 | NodeJS | 20 | Alpine Linux | of-watchdog | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/node20)
 | bun-express | Bun | 1.0 | Alpine Linux | of-watchdog | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/bun-express)
 | node | NodeJS | 20 | Alpine Linux | classic | [NodeJS template](https://github.com/openfaas/templates/tree/master/template/node)
 | python3 | Python | 3 | Alpine Linux | classic | [Python 3 template](https://github.com/openfaas/templates/tree/master/template/python3)