Add bash example readme, and add emphasis on warning about deploying sample apps.

README.md

@@ -63,11 +63,11 @@ of how it is implemented:
 * [php](./php/README.md)
 * [python](./python/README.md)
 
-All of these examples are illustrative and simply demonstrate how the Photo API can be queried
-from code. They are not intended for production use and should not be deployed to environments
-where they can be accessed without authentication.
+**Important** All of these examples are illustrative and simply demonstrate how the Photo API can
+be queried from code. They are not intended for production use and should not be deployed to
+environments where they can be accessed without authentication.
 
-### Prerequisite
+### Prerequisites
 
 All of the samples have been dockerized and contain a readme with instructions for running the
 sample either via docker-compose or without docker with local dependencies.

bash/README.md

+# Photo API Bash sample
+
+This directory contains an example bash script which authenticates with the API Gateway and queries
+the Photo API for a photo by identifier. It makes use of `curl` to interact with the Photo API and
+`jq` to parse the access token response.
+
+## Running the example
+
+With both [`jq`](https://stedolan.github.io/jq/) and [`curl`](https://curl.se/) installed locally,
+and `../secrets.env` populated as specified in `../secrets.example.env`, the script can be run
+using:
+
+```sh
+./example.sh <identifier> > example.jpeg
+```
+
+For example, the following would fetch a photo of the person with the CRSid `wgd23`:
+
+```sh
+./example.sh wgd23@v1.person.identifiers.cam.ac.uk > wgd23.jpeg
+```
+
+The example can also be run using Docker and Docker Compose, which does not require `curl` or `jq`
+to be installed locally:
+
+```sh
+docker-compose run bash-example <identifier>
+```
+
+This will output the fetched photo to `./output/example.jpeg`.
+
+## Interactions with the Photo API
+
+The [example script](./example.sh) contains all commands used to query the Photo API and includes
+comments indicating the purpose of each block. The script fetches a new access token using `curl`,
+making use of the credentials defined in `../secrets.env`, and then uses this access token to
+query the Photo API, again making use of `curl`. If the Photo API or access token request fail
+an error will be logged and the script will exit with an unsuccessful error code.