Add working URL for ICMP types and codes

[roooms]

Changes proposed in this pull request:

• Add new URL for ICMP types and codes as existing one 404s

[bflad]

Hi @roooms! Thanks for finding and submitting this! It looks like we also have that broken URL present in some of the other documentation and code as well:

aws/resource_aws_network_acl_rule.go:	// of ICMP codes and types, see: http://www.nthelp.com/icmp.html
website/docs/r/default_network_acl.html.markdown:~> Note: For more information on ICMP types and codes, see here: http://www.nthelp.com/icmp.html
website/docs/r/network_acl_rule.html.markdown:~> Note: For more information on ICMP types and codes, see here: http://www.nthelp.com/icmp.html
website/docs/r/network_acl.html.markdown:~> Note: For more information on ICMP types and codes, see here: http://www.nthelp.com/icmp.html

Do you mind fixing those up too?

[roooms]

Hey @bflad, sorry I didn't check for that before. The second commit updates all instances of the broken link.

[bflad]

Thanks so much, @roooms! 🚀

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!