doc: add a README file with a few examples.

Author: Pavel910

README.md

@@ -1 +1,90 @@
 # Template
+
+This component is used behind the scenes to deploy your YAML templates. It is loaded by the serverless CLI and executed just as any other component.
+However, there's a lot you can do with this component programmatically. See the sections below for some examples.
+
+### Programmatic usage and custom environments
+
+To deploy to multiple environments you must utilize the programmatic API, via `serverless.js` file.
+
+`serverless.js`
+
+```js
+const { Component } = require('@serverless/core')
+
+class Deploy extends Component {
+  async default(inputs = {}) {
+    const { env } = inputs
+
+    const template = await this.load('@serverless/template', env)
+    return await template({ template: __dirname + '/serverless.yml' })
+  }
+
+  async remove(inputs = {}) {
+    const { env } = inputs
+
+    const template = await this.load('@serverless/template', env)
+    await template.remove(inputs)
+  }
+}
+
+module.exports = Deploy
+```
+
+`serverless.yml`
+
+```yml
+name: test
+
+lambda:
+  component: '@serverless/function'
+  inputs:
+    name: my-function
+    description: My Serverless Function
+    memory: 128
+    timeout: 20
+    code: './code'
+    hanlder": 'handler.handler'
+    region: us-east-1
+    runtime: nodejs10.x
+```
+
+Invoking `sls --env=dev` will result in state files in `.serverless/` being prefixed with the value of your `env`:
+`Deploy.dev.json`, etc. That way you can deploy unlimited environments, add pre/post processing, load whatever `.env` you need, etc.
+
+### Running custom methods on a template
+
+A template itself does not contain any methods so custom methods are executed on the specific template aliases.
+
+`sls install --component lambda` will load the `lambda` alias from your template, instantiate the corresponding component, and execute the `install` method passing in the inputs you specify via CLI parameters.
+Inputs from the template itself are not passed as they can not be interpreted/resolved without running the entire template.
+
+You can pass as many `--component` parameters as you need.
+
+### Running custom methods programmatically
+
+`serverless.js`
+
+```js
+const { Component } = require('@serverless/core')
+
+class Deploy extends Component {
+  /* ...skipped default method for brevity ... */
+
+  async install(inputs = {}) {
+    const template = await this.load('@serverless/template')
+    await template.install({ template: __dirname + '/serverless.yml', ...inputs })
+  }
+}
+
+module.exports = Deploy
+```
+
+When invoking methods on a `template` instance, you always need to pass in a path to the template file or a template object.
+
+Running `sls install --component lambda --debug` - this will load the template, find the `lambda` alias, and invoke the `install` method on the instance of the component.
+
+### Couldn't find what you were looking for?
+
+Visit our github and file an issue with as much info as possible about your problem.
+If you think you've found a bug - please do post a complete reproduction repo. It will help us and our contributors to help you much faster.