Add simple Builder for the hello_world recipe

This is from LUCI's onboarding docs

Change-Id: Ifb373f87be6d7d378a8c9785af5d9d24915282d5

generated/cr-buildbucket.cfg

diff --git a/generated/cr-buildbucket.cfg b/generated/cr-buildbucket.cfg
index 5c8967b..0e23f27 100644
--- a/generated/cr-buildbucket.cfg
+++ b/generated/cr-buildbucket.cfg
@@ -6,6 +6,25 @@
 
 buckets {
   name: "ci"
+  swarming {
+    builders {
+      name: "Example Builder"
+      swarming_host: "chromium-swarm.appspot.com.appspot.com"
+      exe {
+        cipd_package: "infra/recipe_bundles/gerrit.googlesource.com/luci-config"
+        cipd_version: "refs/heads/main"
+        cmd: "luciexe"
+      }
+      properties:
+        '{'
+        '  "recipe": "hello_world"'
+        '}'
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+    }
+  }
 }
 buckets {
   name: "prod"

generated/luci-scheduler.cfg

diff --git a/generated/luci-scheduler.cfg b/generated/luci-scheduler.cfg
new file mode 100644
index 0000000..9b580dc
--- /dev/null
+++ b/generated/luci-scheduler.cfg
@@ -0,0 +1,16 @@
+# Auto-generated by lucicfg.
+# Do not modify manually.
+#
+# For the schema of this file, see ProjectConfig message:
+#   https://luci-config.appspot.com/schemas/projects:luci-scheduler.cfg
+
+job {
+  id: "Example Builder"
+  realm: "ci"
+  schedule: "with 1m interval"
+  buildbucket {
+    server: "cr-buildbucket.appspot.com"
+    bucket: "ci"
+    builder: "Example Builder"
+  }
+}

main.star

diff --git a/main.star b/main.star
index 0a51661..d79510b 100755
--- a/main.star
+++ b/main.star
@@ -66,3 +66,32 @@
 # The prod bucket will include builders which work on post-commit code and
 # generate executable artifacts used by other users or machines.
 luci.bucket(name = "prod")
+
+# Builders
+
+# This is the cipd package where the recipe bundler will put the built recipes.
+# This line makes it the default value for all `luci.recipe` invocations in
+# this configuration.
+luci.recipe.defaults.cipd_package.set("infra/recipe_bundles/gerrit.googlesource.com/luci-config")
+
+# This sets the default CIPD ref to use in builds to get the right version of
+# recipes for the build.
+#
+# The recipe bundler sets CIPD refs equal in name to the git refs that it
+# processed the recipe code from.
+#
+# Note: This will cause all recipe commits to automatically deploy as soon
+# as the recipe bundler compiles them from your refs/heads/main branch.
+cipd_version = "refs/heads/main"
+
+luci.builder(
+  name = "Example Builder",
+  bucket = "ci",
+
+  executable = luci.recipe(
+    # The name of the recipe we just added.
+    name = "hello_world",
+  ),
+
+  schedule = "with 1m interval",
+)