Update GitLab Serverless documentation to use `gitlabktl`

doc/user/project/clusters/serverless/index.md

@@ -91,10 +91,11 @@ Using functions is useful for dealing with independent
 events without needing to maintain a complex unified infrastructure. This allows
 you to focus on a single task that can be executed/scaled automatically and independently.
 
-Currently the following [runtimes](https://gitlab.com/triggermesh/runtimes) are offered:
+Currently the following [runtimes](https://gitlab.com/gitlab-org/serverless/runtimes) are offered:
 
+- ruby
 - node.js
-- kaniko
+- Dockerfile
 
 You can find and import all the files referenced in this doc in the **[functions example project](https://gitlab.com/knative-examples/functions)**.
 
@@ -113,13 +114,17 @@ Follow these steps to deploy a function using the Node.js runtime to your Knativ
    include:
      template: Serverless.gitlab-ci.yml
 
-   functions:
+   functions:build:
+     extends: .serverless:build:functions
+     environment: production
+
+   functions:deploy:
      extends: .serverless:deploy:functions
      environment: production
    ```
 
-    This `.gitlab-ci.yml` creates a `functions` job that invokes some
-    predefined commands to deploy your functions to your cluster.
+    This `.gitlab-ci.yml` creates jobs that invokes some predefined commands to
+    build and deploy your functions to your cluster.
 
     `Serverless.gitlab-ci.yml` is a template that allows customization.
     You can either import it with `include` parameter and use `extends` to
@@ -137,29 +142,40 @@ Follow these steps to deploy a function using the Node.js runtime to your Knativ
    You can find the relevant files for this project in the [functions example project](https://gitlab.com/knative-examples/functions).
 
    ```yaml
-   service: my-functions
-   description: "Deploying functions from GitLab using Knative"
+   service: functions
+   description: "GitLab Serverless functions using Knative"
 
    provider:
      name: triggermesh
-     registry-secret: gitlab-registry
      environment:
-       FOO: BAR
+       FOO: value
 
  	 functions:
-     echo:
-       handler: echo
-       runtime: https://gitlab.com/triggermesh/runtimes/raw/master/nodejs.yaml
-       description: "echo function using node.js runtime"
-       buildargs:
-        - DIRECTORY=echo
+		 echo-js:
+			 handler: echo-js
+			 source: ./echo-js
+			 runtime: https://gitlab.com/gitlab-org/serverless/runtimes/nodejs
+			 description: "node.js runtime function"
+			 environment:
+				 MY_FUNCTION: echo-js
+
+		 echo-rb:
+			 handler: MyEcho.my_function
+			 source: ./echo-rb
+			 runtime: https://gitlab.com/gitlab-org/serverless/runtimes/ruby
+			 description: "Ruby runtime function"
+			 environment:
+				 MY_FUNCTION: echo-rb
+
+		 echo-docker:
+			 handler: echo-docker
+			 source: ./echo-docker
+			 description: "Dockerfile runtime function"
 			 environment:
-        FUNCTION: echo
+				 MY_FUNCTION: echo-docker
    ```
 
-The `serverless.yml` file references both an `echo` directory (under `buildargs`) and an `echo` file (under `handler`),
-which is a reference to `echo.js` in the [repository](https://gitlab.com/knative-examples/functions). Additionally, it
-contains three sections with distinct parameters:
+Explanation of fields used above:
 
 ### `service`
 
@@ -173,7 +189,6 @@ contains three sections with distinct parameters:
 | Parameter | Description |
 |-----------|-------------|
 | `name` | Indicates which provider is used to execute the `serverless.yml` file. In this case, the TriggerMesh `tm` CLI. |
-| `registry-secret` | Indicates which registry will be used to store docker images. The sample function is using the GitLab Registry (`gitlab-registry`). A different registry host may be specified using `registry` key in the `provider` object. If changing the default, update the permission and the secret value on the `gitlab-ci.yml` file |
 | `environment` | Includes the environment variables to be passed as part of function execution for **all** functions in the file, where `FOO` is the variable name and `BAR` are he variable contents. You may replace this with you own variables. |
 
 ### `functions`
@@ -182,10 +197,10 @@ In the `serverless.yml` example above, the function name is `echo` and the subse
 
 | Parameter | Description |
 |-----------|-------------|
-| `handler` | The function's file name. In the example above, both the function name and the handler are the same. |
+| `handler` | The function's name. |
+| `source` | Directory with sources of a functions. |
 | `runtime` | The runtime to be used to execute the function. |
 | `description` | A short description of the function. |
-| `buildargs` | Pointer to the function file in the repo. In the sample the function is located in the `echo` directory. |
 | `environment` | Sets an environment variable for the specific function only. |
 
 After the `gitlab-ci.yml` template has been added and the `serverless.yml` file has been