docs: add docs on extra providers attribute #3029

Author: kamilmysliwiec

content/techniques/caching.md

@@ -11,9 +11,10 @@ $ npm install @nestjs/cache-manager cache-manager
 ```
 
 > warning **Warning** `cache-manager` version 4 uses seconds for `TTL (Time-To-Live)`. The current version of `cache-manager` (v5) has switched to using milliseconds instead. NestJS doesn't convert the value, and simply forwards the ttl you provide to the library. In other words:
-> * If using `cache-manager` v4, provide ttl in seconds
-> * If using `cache-manager` v5, provide ttl in milliseconds
-> * Documentation is referring to seconds, since NestJS was released targeting version 4 of cache-manager.
+>
+> - If using `cache-manager` v4, provide ttl in seconds
+> - If using `cache-manager` v5, provide ttl in milliseconds
+> - Documentation is referring to seconds, since NestJS was released targeting version 4 of cache-manager.
 
 #### In-memory cache
 
@@ -315,6 +316,18 @@ This works the same as `useClass` with one critical difference - `CacheModule` w
 
 > info **Hint** `CacheModule#register` and `CacheModule#registerAsync` and `CacheOptionsFactory` has an optional generic (type argument) to narrow down store-specific configuration options, making it type safe.
 
+You can also pass so-called `extraProviders` to the `registerAsync()` method. These providers will be merged with the module providers.
+
+```typescript
+CacheModule.registerAsync({
+  imports: [ConfigModule],
+  useClass: ConfigService,
+  extraProviders: [MyAdditionalProvider],
+});
+```
+
+This is useful when you want to provide additional dependencies to the factory function or the class constructor.
+
 #### Example
 
 A working example is available [here](https://github.com/nestjs/nest/tree/master/sample/20-cache).

content/techniques/file-upload.md

@@ -118,7 +118,7 @@ export abstract class FileValidator<TValidationOptions = Record<string, any>> {
 `FileValidator` is a regular class that has access to the file object and validates it according to the options provided by the client. Nest has two built-in `FileValidator` implementations you can use in your project:
 
 - `MaxFileSizeValidator` - Checks if a given file's size is less than the provided value (measured in `bytes`)
-- `FileTypeValidator` - Checks if a given file's mime-type matches the given value. 
+- `FileTypeValidator` - Checks if a given file's mime-type matches the given value.
 
 > warning **Warning** To verify file type, [FileTypeValidator](https://github.com/nestjs/nest/blob/master/packages/common/pipes/file/file-type.validator.ts) class uses the type as detected by multer. By default, multer derives file type from file extension on user's device. However, it does not check actual file contents. As files can be renamed to arbitrary extensions, consider using a custom implementation (like checking the file's [magic number](https://www.ibm.com/support/pages/what-magic-number)) if your app requires a safer solution.
 
@@ -135,6 +135,7 @@ To understand how these can be used in conjunction with the aforementioned `File
 )
 file: Express.Multer.File,
 ```
+
 > info **Hint** If the number of validators increase largely or their options are cluttering the file, you can define this array in a separate file and import it here as a named constant like `fileValidators`.
 
 Finally, you can use the special `ParseFilePipeBuilder` class that lets you compose & construct your validators. By using it as shown below you can avoid manual instantiation of each validator and just pass their options directly:
@@ -318,6 +319,18 @@ MulterModule.registerAsync({
 });
 ```
 
+You can also pass so-called `extraProviders` to the `registerAsync()` method. These providers will be merged with the module providers.
+
+```typescript
+MulterModule.registerAsync({
+  imports: [ConfigModule],
+  useClass: ConfigService,
+  extraProviders: [MyAdditionalProvider],
+});
+```
+
+This is useful when you want to provide additional dependencies to the factory function or the class constructor.
+
 #### Example
 
 A working example is available [here](https://github.com/nestjs/nest/tree/master/sample/29-file-upload).

content/techniques/http-module.md

@@ -132,6 +132,18 @@ HttpModule.registerAsync({
 });
 ```
 
+You can also pass so-called `extraProviders` to the `registerAsync()` method. These providers will be merged with the module providers.
+
+```typescript
+HttpModule.registerAsync({
+  imports: [ConfigModule],
+  useClass: HttpConfigService,
+  extraProviders: [MyAdditionalProvider],
+});
+```
+
+This is useful when you want to provide additional dependencies to the factory function or the class constructor.
+
 #### Using Axios directly
 
 If you think that `HttpModule.register`'s options are not enough for you, or if you just want to access the underlying Axios instance created by `@nestjs/axios`, you can access it via `HttpService#axiosRef` as follows: