Fix typos, update types and add comments

Signed-off-by: Clément Blaise <clementblaise@me.com>

request/request.go

@@ -129,17 +129,17 @@ func GetExtraResources(req *v1beta1.RunFunctionRequest) (map[string][]resource.E
 	return out, nil
 }
 
-// GetCredential from the supplied request.
-func GetCredential(req *v1beta1.RunFunctionRequest, name string) (resource.Credential, error) {
+// GetCredentials from the supplied request.
+func GetCredentials(req *v1beta1.RunFunctionRequest, name string) (resource.Credentials, error) {
 	cred, exists := req.GetCredentials()[name]
 	if !exists {
-		return resource.Credential{}, errors.Errorf("%s: credential not found", name)
+		return resource.Credentials{}, errors.Errorf("%s: credential not found", name)
 	}
 
 	switch t := cred.GetSource().(type) {
 	case *v1beta1.Credentials_CredentialData:
-		return resource.Credential{Type: resource.CredentialsTypeData, Data: cred.GetCredentialData().GetData()}, nil
+		return resource.Credentials{Type: resource.CredentialsTypeData, Data: cred.GetCredentialData().GetData()}, nil
 	default:
-		return resource.Credential{}, errors.Errorf("%s: not a supported credential source", t)
+		return resource.Credentials{}, errors.Errorf("%s: not a supported credential source", t)
 	}
 }

resource/resource.go

@@ -57,17 +57,21 @@ type Extra struct {
 	Resource *unstructured.Unstructured
 }
 
-// CredentialsType is the type of credentials
+// CredentialsType is the type of credentials.
 type CredentialsType string
 
 const (
-	// CredentialsTypeData is a Credential which of type Data
+	// CredentialsTypeData is a Credential of type Data.
 	CredentialsTypeData = "Data"
 )
 
-// Credential is a secret requested by a Function
-type Credential struct {
+// Credentials is a secret requested by a Function.
+type Credentials struct {
+	// Type represents the type of credentials.
 	Type CredentialsType
+
+	// Data is a map of key-value pairs where the keys are strings, and the values are byte slices
+	// containing sensitive data.
 	Data map[string][]byte
 }