Add detailed examples for macOS, Linux, Windows

docs/http_proxy.md

 ## Using Minikube with an HTTP Proxy
 
-Minikube creates a Virtual Machine that includes Kubernetes and a Docker daemon.
-When Kubernetes attempts to schedule containers using Docker, the Docker daemon may require external network access to pull containers.
+minikube requires access to the internet via HTTP, HTTPS, and DNS protocols. If a HTTP proxy is required to access the internet, you may need to pass the proxy connection information to both minikube and Docker using environment variables:
 
-If you are behind an HTTP proxy, you may need to supply Docker with the proxy settings.
-To do this, pass the required environment variables as flags during `minikube start`.
+* HTTP_PROXY - The URL to your HTTP proxy
+* HTTPS_PROXY - The URL to your HTTPS proxy
+* NO_PROXY - A comma-separated list of hosts which should not go through the proxy.
 
-For example:
+The NO_PROXY variable here is important: Without setting it, minikube may not be able to access resources within the VM. minikube has two important ranges of internal IP's:
+
+* 192.168.0.0/12: Used by the minikube VM. Configurable for some hypervisors via `--host-only-cidr`
+* 10.96.0.0/12: Used by service cluster IP's. Configurable via  `--service-cluster-ip-range`
+
+## Example Usage
+
+### macOS and Linux
 
-```shell
-$ minikube start --docker-env=HTTP_PROXY=http://$YOURPROXY:PORT \
-                 --docker-env=HTTPS_PROXY=https://$YOURPROXY:PORT
 ```
+export HTTP_PROXY=http://<proxy hostname:port>
+export HTTPS_PROXY=https://<proxy hostname:port>
+export NO_PROXY=localhost,127.0.0.1,10.96.0.0/12,192.168.0.0/16
+
+minikube start --docker-env=HTTP_PROXY=$HTTP_PROXY --docker-env HTTPS_PROXY=$HTTPS_PROXY
+```
+
+To make the exported variables permanent, consider adding the declarations to ~/.bashrc or wherever your user-set environment variables are stored.
 
-If your Virtual Machine address is 192.168.99.100, then chances are your proxy settings will prevent kubectl from directly reaching it.
-To by-pass proxy configuration for this IP address, you should modify your no_proxy settings. You can do so with:
+### Windows
 
-```shell
-$ export no_proxy=$no_proxy,$(minikube ip)
 ```
+set HTTP_PROXY=http://<proxy hostname:port>
+set HTTPS_PROXY=https://<proxy hostname:port>
+set NO_PROXY=localhost,127.0.0.1,10.96.0.0/12,192.168.0.0/16
+
+minikube start --docker-env=HTTP_PROXY=$HTTP_PROXY --docker-env HTTPS_PROXY=$HTTPS_PROXY --docker-env NO_PROXY=$NO_PROXY
+```
+
+To set these environment variables permanently, consider adding these to your [system settings](https://support.microsoft.com/en-au/help/310519/how-to-manage-environment-variables-in-windows-xp) or using [setx](https://stackoverflow.com/questions/5898131/set-a-persistent-environment-variable-from-cmd-exe)
+
+## Additional Information
+
+- [Configure Docker to use a proxy server](https://docs.docker.com/network/proxy/)