fix: the sdk node example

[DNR500]

JIra: LF-8254

WIP To get this working you need to add your private key. You can do this by

• duplicating the .env-template file
• renaming it to .env
• replacing the text in quote marks with your private key

I’m current working examples

• example/swap.ts which can be run on yarn example:swap
• example/bridge.ts which can be run on yarn example:bridge

Still to do

• update the other examples
• update the readme