✏️ [Readme Enhancement] - Fix Dead Links in Readme and add Dead Link Checker Github Action

[Aman035]

Expected Behaviour

• A couple of links point to push-protocol rather than pushchain.
• A github action which can check for dead links on every PR would automate the detection process

[ANAMASGARD]

@Aman035 I HAVE RAISED A PR PLEASE CAN YOU REVIEW IT AND GIVE YOUR FEEDBACK !

#236