Add comments explaining the repo path

Author: spencertransier

.buildkite/cache-builder.yml

@@ -10,6 +10,9 @@ common_params:
     - automattic/bash-cache#2.8.0
     - automattic/git-s3-cache#v1.1.3:
         bucket: "a8c-repo-mirrors"
+        # This is not necessarily the actual name of the repo or the GitHub organization
+        # it belongs to. It is the key used in the bucket, which is set based on
+        # the Buildkite pipeline slug
         repo: "automattic/woocommerce-ios/"
   # Common environment values to use with the `env` key.
   - &common_env

.buildkite/pipeline.yml

@@ -5,6 +5,9 @@ common_params:
     - automattic/bash-cache#2.8.0
     - automattic/git-s3-cache#v1.1.3:
         bucket: "a8c-repo-mirrors"
+        # This is not necessarily the actual name of the repo or the GitHub organization
+        # it belongs to. It is the key used in the bucket, which is set based on
+        # the Buildkite pipeline slug
         repo: "automattic/woocommerce-ios/"
   # Common environment values to use with the `env` key.
   - &common_env

.buildkite/release-builds.yml

@@ -7,6 +7,9 @@ common_params:
     - automattic/bash-cache#2.8.0
     - automattic/git-s3-cache#v1.1.3:
         bucket: "a8c-repo-mirrors"
+        # This is not necessarily the actual name of the repo or the GitHub organization
+        # it belongs to. It is the key used in the bucket, which is set based on
+        # the Buildkite pipeline slug
         repo: "automattic/woocommerce-ios/"
   # Common environment values to use with the `env` key.
   - &common_env