pkgs/shelf_router_generator: README.md example update

[AlexeyBukin]

Replaced old example with current example from /example/main.dart

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[kevmoo]

@AlexeyBukin – mind rebasing and resolving conflicts?

[kevmoo]

Suggested change

	## 1.1.4
	## 1.1.4-wip

[kevmoo]

Suggested change

	version: 1.1.4
	version: 1.1.4-wip