ec2_customer_gateway: bgp_asn is not required

[neilkatin]

Summary

The ec2_customer_gateway module has incorrect documentation for the bgp_asn parameter.

It says the ASN must be passed when state=present, but the code defaults to 25000 if the parameter is absent. See the ensure_cgw_present() method:

    def ensure_cgw_present(self, bgp_asn, ip_address):
        if not bgp_asn:
            bgp_asn = 65000
        response = self.ec2.create_customer_gateway(
            DryRun=False,
            Type='ipsec.1',
            PublicIp=ip_address,
            BgpAsn=bgp_asn,
        )
        return response

### Issue Type

Documentation Report

### Component Name

ec2_customer_gateway

### Ansible Version

```console (paste below)
$ ansible --version
ansible [core 2.12.4]
  config file = None
  configured module search path = ['/home/neil/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /home/neil/.local/share/virtualenvs/community.aws-uRL047Ho/lib/python3.10/site-packages/ansible
  ansible collection location = /home/neil/.ansible/collections:/usr/share/ansible/collections
  executable location = /home/neil/.local/share/virtualenvs/community.aws-uRL047Ho/bin/ansible
  python version = 3.10.1 (main, Jan 10 2022, 00:00:00) [GCC 11.2.1 20211203 (Red Hat 11.2.1-7)]
  jinja version = 3.1.1
  libyaml = True

Collection Versions

$ ansible-galaxy collection list

Configuration

$ ansible-config dump --only-changed

OS / Environment

main branch, as of 2022-04-18.

Additional Information

Suggested rewording:

options:
  bgp_asn:
    description:
      - Border Gateway Protocol (BGP) Autonomous System Number (ASN), defaults to 25000.
    type: int

Code of Conduct

• I agree to follow the Ansible Code of Conduct

[ansibullbot]

Files identified in the description:

• [plugins/modules/ec2_customer_gateway.py](https://github.com/['ansible-collections/amazon.aws', 'ansible-collections/community.aws', 'ansible-collections/community.vmware']/blob/main/plugins/modules/ec2_customer_gateway.py)

If these files are inaccurate, please update the component name section of the description or use the !component bot command.

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[ansibullbot]

cc @MichaelBaydoun @jillr @markuman @s-hertel @tremble
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[alinabuzachis]

@neilkatin Thank you for raising this. bgp_asn shouldn't be a required parameter anymore since it defaults to 65000 as reported in the boto3 documentation. https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ec2.html#EC2.Client.create_customer_gateway

Would you be willing to open a pull request to fix that inconsistency?