docs: document module providers in plugins (#11360)

* docs: document module providers in plugins

* small fixes

* add missing title

www/apps/resources/references/auth_provider/classes/auth_provider.AbstractAuthModuleProvider/page.mdx

@@ -10,9 +10,18 @@ In this document, you’ll learn how to create an auth provider module and the m
 
 ---
 
-## 1. Create Module Directory
+## 1. Create Module Provider Directory
 
-Start by creating a new directory for your module. For example, `src/modules/my-auth`.
+Start by creating a new directory for your module provider.
+
+If you're creating the module provider in a Medusa application, create it under the `src/modules` directory. For example, `src/modules/my-auth`.
+If you're creating the module provider in a plugin, create it under the `src/providers` directory. For example, `src/providers/my-auth`.
+
+<Note>
+
+The rest of this guide always uses the `src/modules/my-auth` directory as an example.
+
+</Note>
 
 ---
 
@@ -479,6 +488,7 @@ module.exports = defineConfig({
             id: "emailpass",
           },
           {
+            // if module provider is in a plugin, use `plugin-name/providers/my-auth`
             resolve: "./src/modules/my-auth",
             id: "my-auth",
             dependencies: [Modules.CACHE, ContainerRegistrationKeys.LOGGER],

www/apps/resources/references/file/classes/file.AbstractFileProviderService/page.mdx

@@ -10,9 +10,18 @@ In this document, you’ll learn how to create a file provider module and the me
 
 ---
 
-## 1. Create Module Directory
+## Create Module Provider Directory
 
-Start by creating a new directory for your module. For example, `src/modules/my-file`.
+Start by creating a new directory for your module provider.
+
+If you're creating the module provider in a Medusa application, create it under the `src/modules` directory. For example, `src/modules/my-file`.
+If you're creating the module provider in a plugin, create it under the `src/providers` directory. For example, `src/providers/my-file`.
+
+<Note>
+
+The rest of this guide always uses the `src/modules/my-file` directory as an example.
+
+</Note>
 
 ---
 
@@ -251,6 +260,7 @@ module.exports = defineConfig({
             id: "local",
           },
           {
+            // if module provider is in a plugin, use `plugin-name/providers/my-file`
             resolve: "./src/modules/my-file",
             id: "my-file",
             options: {

www/apps/resources/references/fulfillment_provider/classes/fulfillment_provider.AbstractFulfillmentProviderService/page.mdx

@@ -10,9 +10,18 @@ In this document, you’ll learn how to create a fulfillment provider module and
 
 ---
 
-## 1. Create Module Directory
+## 1. Create Module Provider Directory
 
-Start by creating a new directory for your module. For example, `src/modules/my-fulfillment`.
+Start by creating a new directory for your module provider.
+
+If you're creating the module provider in a Medusa application, create it under the `src/modules` directory. For example, `src/modules/my-fulfillment`.
+If you're creating the module provider in a plugin, create it under the `src/providers` directory. For example, `src/providers/my-fulfillment`.
+
+<Note>
+
+The rest of this guide always uses the `src/modules/my-fulfillment` directory as an example.
+
+</Note>
 
 ---
 
@@ -534,6 +543,7 @@ module.exports = defineConfig({
             id: "manual",
           },
           {
+            // if module provider is in a plugin, use `plugin-name/providers/my-fulfillment`
             resolve: "./src/modules/my-fulfillment",
             id: "my-fulfillment",
             options: {

www/apps/resources/references/notification/classes/notification.AbstractNotificationProviderService/page.mdx

@@ -10,9 +10,18 @@ In this document, you’ll learn how to create a notification provider module an
 
 ---
 
-## 1. Create Module Directory
+## 1. Create Module Provider Directory
 
-Start by creating a new directory for your module. For example, `src/modules/my-notification`.
+Start by creating a new directory for your module provider.
+
+If you're creating the module provider in a Medusa application, create it under the `src/modules` directory. For example, `src/modules/my-notification`.
+If you're creating the module provider in a plugin, create it under the `src/providers` directory. For example, `src/providers/my-notification`.
+
+<Note>
+
+The rest of this guide always uses the `src/modules/my-notification` directory as an example.
+
+</Note>
 
 ---
 
@@ -192,6 +201,7 @@ module.exports = defineConfig({
             },
           },
           {
+            // if module provider is in a plugin, use `plugin-name/providers/my-notification`
             resolve: "./src/modules/my-notification",
             id: "my-notification",
             options: {

www/apps/resources/references/payment_provider/classes/payment_provider.AbstractPaymentProvider/page.mdx

@@ -10,9 +10,18 @@ In this document, you’ll learn how to create a Payment Provider to be used wit
 
 ---
 
-## 1. Create Module Directory
+## 1. Create Module Provider Directory
 
-Start by creating a new directory for your module. For example, `src/modules/my-payment`.
+Start by creating a new directory for your module provider.
+
+If you're creating the module provider in a Medusa application, create it under the `src/modules` directory. For example, `src/modules/my-payment`.
+If you're creating the module provider in a plugin, create it under the `src/providers` directory. For example, `src/providers/my-payment`.
+
+<Note>
+
+The rest of this guide always uses the `src/modules/my-payment` directory as an example.
+
+</Note>
 
 ---
 
@@ -742,6 +751,7 @@ module.exports = defineConfig({
       options: {
         providers: [
           {
+            // if module provider is in a plugin, use `plugin-name/providers/my-payment`
             resolve: "./src/modules/my-payment",
             id: "my-payment",
             options: {