docs(apk): document apkindex methods

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>

pkg/apk/apk/index.go

@@ -202,7 +202,12 @@ func (i *indexCache) get(ctx context.Context, repoName, repoURL string, keys map
 	}
 }
 
-// IndexURL full URL to the index file for the given repo and arch
+// IndexURL returns the full URL to the index file for the given repo and arch.
+//
+// `repo` is the URL of the repository including the protocol, e.g.
+// "https://packages.wolfi.dev/os".
+//
+// `arch` is the architecture of the index, e.g. "x86_64" or "aarch64".
 func IndexURL(repo, arch string) string {
 	return fmt.Sprintf("%s/%s/%s", repo, arch, indexFilename)
 }

pkg/apk/client/client.go

@@ -37,6 +37,11 @@ func New(httpClient *http.Client) *Client {
 
 // GetRemoteIndex retrieves the index of APK packages from the specified remote
 // repository.
+//
+// `apkRepo` is the URL of the repository including the protocol, e.g.
+// "https://packages.wolfi.dev/os".
+//
+// `arch` is the architecture of the index, e.g. "x86_64" or "aarch64".
 func (c Client) GetRemoteIndex(ctx context.Context, apkRepo, arch string) (*apk.APKIndex, error) {
 	indexURL := apk.IndexURL(apkRepo, arch)