add FAQ for deploy command

Author: baldarn

Gemfile.lock

@@ -42,6 +42,7 @@ GEM
     faraday-net_http (3.3.0)
       net-http
     ffi (1.17.0-arm64-darwin)
+    ffi (1.17.0-x86_64-linux-gnu)
     forwardable-extended (2.6.0)
     gemoji (4.1.0)
     github-pages (232)
@@ -232,6 +233,8 @@ GEM
       uri
     nokogiri (1.16.7-arm64-darwin)
       racc (~> 1.4)
+    nokogiri (1.16.7-x86_64-linux)
+      racc (~> 1.4)
     octokit (4.25.1)
       faraday (>= 1, < 3)
       sawyer (~> 0.9)
@@ -270,6 +273,7 @@ PLATFORMS
   arm64-darwin-22
   arm64-darwin-23
   arm64-darwin-24
+  x86_64-linux
 
 DEPENDENCIES
   github-pages

docs/commands/deploy.md

@@ -37,3 +37,25 @@ Options:
   -H, [--skip-hooks]                                 # Don't run hooks
                                                      # Default: false
 ```
+
+# FAQ
+
+## Skip building an deploy some public docker image
+
+See [this Github issue](https://github.com/basecamp/kamal/issues/497)
+
+In order to use pre build images, you have to add a `service` label with the name of kamal service.
+
+For example, a `deploy.yml` file starting with:
+
+```yaml
+# Name of your application. Used to uniquely configure containers.
+service: name-of-service
+
+# Name of the container image.
+image: some/image
+
+...
+```
+
+will require the label `label=service=name-of-service`.