Add zarf prepare docs

docs/prepare.md

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+# Zarf Prepare Command
+
+`zarf prepare ...`
+
+## Using Zarf prepare to list chart images
+
+1. Download the zarf binary from [releases](https://repo1.dso.mil/platform-one/big-bang/apps/product-tools/zarf/-/releases) [reference](workstation.md#install)
+2. `zarf tools registry login <registry_name> -u <username> -p <secret>`
+3.  `zarf prepare find-images -p /chart` # Ran next in the same directory as a zarf.yaml file
+
+
+### Breaking it down
+
+
+**The Zarf Binary**   
+See [README](../README.md) for more details about zarf. Add `zarf` binary to your path and make it executable for ease of use i.e. `export PATH=$PATH:/path/to/zarf/binary && chmod +x /path/to/zarf/binary/zarf`
+
+**zarf tools registry login...**  
+This command is a utility of Zarf to help create a Zarf package. In other zarf commands (like `zarf prepare find-images`) the package images will be validated against a live registry! The registry login is stored in your docker config, typically stored in `~/.docker/config.json` and zarf commands don't require a container runtime (i.e. docker daemon, podman instance, etc...).
+
+**zarf prepare find-images -p /chart**  
+This command discovers images used in a helm chart.  Try out this quick example:
+
+`git clone https://github.com/defenseunicorns/zarf.git`
+`cd zarf/examples/tiny-kafka`
+`zarf prepare find-images -p /chart`
+You should see output similar to:
+```shell
+  ✔  Processing helm chart strimzi-kafka-operator:0.24.0 from repo https://strimzi.io/charts/
+  ✔  Copying charts/strimzi-values.yaml
+  ✔  Templating helm chart strimzi-kafka-operator
+      # kafka-strimzi-demo - baseline
+      - registry1.dso.mil/ironbank/opensource/strimzi/operator:0.24.0
+      # Possible images - kafka-strimzi-demo - baseline
+      - registry1.dso.mil/ironbank/opensource/strimzi/kafka:0.24.0-kafka-2.8.0
+```
+
+If you inspect the zarf.yaml, you'll notice those two images are specified...   
+No, we aren't cheating. Delete the `images:` block in the zarf.yaml and rerun `zarf prepare find-images -p /chart`...  
+The output is the same :)   
+Zarf is inspecting the helm chart specified by the directory `-p /chart` flag. The kafka image isn't even specified in the chart, but it's deployed by the operator.
+
+
+**The zarf.yaml** 
+The zarf.yaml file is used specify a zarf package configuration. For the find-images command, all we really need is a ZarfPackageConfig with a component specified.
+```yaml
+kind: ZarfPackageConfig
+
+components:
+  - name: baseline
+    charts:
+      - name: strimzi-kafka-operator
+        url: https://strimzi.io/charts/
+        version: 0.24.0
+        valuesFiles:
+          - charts/strimzi-values.yaml
+```