Add CLI examples for CloudWatch Synthetics

[ashishbharadwajm]

Issue #, if available:

Description of changes:

Adding example CLI commands for Amazon CloudWatch Synthetics: https://docs.aws.amazon.com/cli/latest/reference/synthetics/

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[elysahall]

Hi Ashish,
Thank you for your command example submission. I've finished reviewing your pull request. Please fix these formatting issues and push your updated commit. Thanks!

[elysahall]

Suggested change

	The following ``associate-resource`` example associates a canary with group named `demo_group``. If the command succeeds, no output is returned. ::
	The following ``associate-resource`` example associates a canary with the group named ``demo_group``. ::

[elysahall]

Suggested change

	--resource-arn arn:aws:synthetics:us-east-1:123456789012:canary:demo_canary
	--resource-arn arn:aws:synthetics:us-east-1:123456789012:canary:demo_canary
	This command produces no output.

[elysahall]

Suggested change

	The following ``associate-resource`` example associates a canary with group named `demo_group``.
	The following ``associate-resource`` example associates a canary with a group named ``demo_group``. ::

[elysahall]

Suggested change

	**To Associate a canary with a group**
	**To associate a canary with a group**

[elysahall]

Suggested change

	**To Create a canary**
	**To create a canary**

[elysahall]

Suggested change

	The following ``untag-resource`` example removes a tag from the canary named ``demo_canary``.
	The following ``untag-resource`` example removes a tag from the canary named ``demo_canary``. ::

[elysahall]

Suggested change

	**Example 2: To Remove a tag from the group**
	**Example 2: To remove a tag from the group**

[elysahall]

Suggested change

	The following ``untag-resource`` example assigns a removes a tag from the group named ``demo_group``.
	The following ``untag-resource`` example assigns a removes a tag from the group named ``demo_group``. ::

[elysahall]

Suggested change

	**To Update a canary**
	**To update a canary**

[elysahall]

Suggested change

	The following ``update-canary`` example updates the configuration of a canary named ``demo_canary``.
	The following ``update-canary`` example updates the configuration of a canary named ``demo_canary``. ::

[ashishdhingra]

@elysahall I guess you tagged wrong person. Please reach out to @ashishbharadwajm.

[ashishbharadwajm]

Hi Ashish, Thank you for your command example submission. I've finished reviewing your pull request. Please fix these formatting issues and push your updated commit. Thanks!

Thank you for the review. Published the new commit with the suggested changes.