Automatic generation of documentation (#818)

* generate a detailed CLI help
* generate a documentation site
* new readme

docs/content/usage/cli/examples.md

@@ -0,0 +1,48 @@
+---
+title: "Examples"
+date: 2019-03-03T16:39:46+01:00
+draft: false
+---
+
+## CLI Examples
+
+Assumes the `lego` binary has permission to bind to ports 80 and 443.
+You can get a pre-built binary from the [releases](https://github.com/xenolf/lego/releases) page.
+If your environment does not allow you to bind to these ports, please read [Port Usage](usage/cli#port-usage).
+
+### Obtain a certificate
+
+```bash
+lego --email="foo@bar.com" --domains="example.com" --http run
+```
+
+(Find your certificate in the `.lego` folder of current working directory.)
+
+### To renew the certificate
+
+```bash
+lego --email="foo@bar.com" --domains="example.com" --http renew
+```
+
+### To renew the certificate only if it expires within 45 days
+
+```bash
+lego --email="foo@bar.com" --domains="example.com" --http renew --days 45
+```
+
+### Obtain a certificate using the DNS challenge
+
+```bash
+AWS_REGION=us-east-1 \
+AWS_ACCESS_KEY_ID=my_id \
+AWS_SECRET_ACCESS_KEY=my_key \
+lego --email="foo@bar.com" --domains="example.com" --dns="route53" run
+```
+
+### Obtain a certificate given a certificate signing request (CSR) generated by something else
+
+```bash
+lego --email="foo@bar.com" --http --csr=/path/to/csr.pem run
+```
+
+(lego will infer the domains to be validated based on the contents of the CSR, so make sure the CSR's Common Name and optional SubjectAltNames are set correctly.)