* add before-you-begin-egress boilerplate and use it in one case
* move the boilerplate into content
* replace before-you-begin section for egress task/examples
* remove egress related details from the boilerplate
* add "configuring NAT devices to drop packets that do not originate at the egress gateways"
* add Network Policy section
* make sentences present tense
* remove the labels
* rewrite the additional security considerations section
* Network Policy -> network policy
* add cleanup step for the configuring HTTPS egress gateway section
* a malicious application attacks -> attackers bypass
* egressgateway -> egress gateway
* kube-system DNS service -> the kube-system DNS service
* test-egress namespace -> the test-egress namespace
* no Istio sidecar was attached -> with no Istio sidecar attached
* must succeed -> will succeed
* by first enabling, then redeploy