Template/blade refusing ssh pub key

[Zero-downtime Deployment to AKS with Jenkins](https://github.com/Azure/azure-quickstart-templates/tree/master/301-jenkins-aks-zero-downtime-deployment)

### Issue Details
No matter what SSH key I was trying, I alway get:
`
{
"telemetryId": "e2463d6e-53e6-47bb-b926-9b219804357a",
"bladeInstanceId": "Blade_dbc94d6ddd8441ad8511f076829cb355_0_0",
"galleryItemId": "Microsoft.Template",
"createBlade": "DeployToAzure",
"code": "InvalidTemplateDeployment",
"message": "The template deployment 'Microsoft.Template' is not valid according to the …\n \"message\": \"The value of parameter linuxProfile.ssh.publicKeys.keyData is invalid. Please see https://aka.ms/aks-naming-rules for more details.\",\n \"target\": \"linuxProfile.ssh.publicKeys.keyData\"\n }. Details: "
}
]
}`
when submitting the provisioning form/blade.

Start with the 301-jenkins-aks-zero-downtime-deployment template linked in the issue and reproduce the provisioning form failure with an SSH public key. Trace the linuxProfile.ssh.publicKeys.keyData parameter against the AKS naming rules; done means the template accepts a valid key and deployment no longer returns InvalidTemplateDeployment.

Written by the indexing model from the issue text.