add tile author guide for new Kiln users

README.md

@@ -14,14 +14,14 @@ Looking at an [example kiln tile](https://github.com/crhntr/hello-tile/tree/main
 To install the `kiln` CLI 
 - install with Homebrew
 
- ```sh
+ ```shell
  brew tap pivotal-cf/kiln https://github.com/pivotal-cf/kiln
  brew install kiln
  ```
 
 - download from the [releases page](https://github.com/pivotal-cf/kiln/releases)
 
- ```sh
+ ```shell
  export KILN_VERSION
  KILN_VERSION="$(curl -H "Accept: application/vnd.github.v3+json" 'https://api.github.com/repos/pivotal-cf/kiln/releases?per_page=1' | jq -r '.[0].name')"
  curl -L -o kiln "https://github.com/pivotal-cf/kiln/releases/download/${KILN_VERSION}/kiln-darwin-${KILN_VERSION}"
@@ -32,7 +32,7 @@ To install the `kiln` CLI
 
 - build from source
 
- ```sh
+ ```shell
  git clone [email protected]:pivotal-cf/kiln.git
  cd kiln
  git checkout 0.60.2
@@ -41,7 +41,7 @@ To install the `kiln` CLI
 
 - copy from a Docker image (to another image)
 
- ```sh
+ ```shell
  docker pull pivotalcfreleng/kiln:latest
  ```