feat(docs): describe addTemplate

docs/3.api/4.advanced/2.kit.md

@@ -1812,9 +1812,74 @@ export default defineNuxtPlugin((nuxtApp) => {
 
 [source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/template.ts)
 
-- `addTemplate(templateOptions)`
-- `addTypeTemplate(templateOptions)`
-- `updateTemplates({ filter?: ResolvedNuxtTemplate => boolean })`
+### `addTemplate`
+
+Renders given template using lodash template during build into the project buildDir.
+
+#### Type
+
+```ts
+function addTemplate (template: NuxtTemplate | string): NuxtTemplate
+
+interface NuxtTemplate {
+  src?: string
+  filename?: string
+  dst?: string
+  options?: Record<string, any>
+  getContents?: (data: Record<string, any>) => string | Promise<string>
+  write?: boolean
+}
+```
+
+#### Parameters
+
+##### `template`
+
+**Type**: `NuxtTemplate | string`
+
+**Required**: `true`
+
+A template object or a string with the path to the template. If a string is provided, it will be converted to a template object with `src` set to the string value. If a template object is provided, it must have the following properties:
+
+- `src` (optional)
+
+  **Type**: `string`
+
+  Path to the template. If `src` is not provided, `getContents` must be provided instead.
+
+- `filename` (optional)
+
+  **Type**: `string`
+
+  Filename of the template. If `filename` is not provided, it will be generated from the `src` path. In this case, the `src` option is required.
+
+- `dst` (optional)
+
+  **Type**: `string`
+
+  Path to the destination file. If `dst` is not provided, it will be generated from the `filename` path and nuxt `buildDir` option.
+
+- `options` (optional)
+
+  **Type**: `Options`
+
+  Options to pass to the template.
+
+- `getContents` (optional)
+
+  **Type**: `(data: Options) => string | Promise<string>`
+
+  A function that will be called with the `options` object. It should return a string or a promise that resolves to a string. If `src` is provided, this function will be ignored.
+
+- `write` (optional)
+  
+    **Type**: `boolean`
+
+    If set to `true`, the template will be written to the destination file. Otherwise, the template will be used only in virtual filesystem.
+
+### `addTypeTemplate(templateOptions)`
+
+### `updateTemplates({ filter?: ResolvedNuxtTemplate => boolean })`
 
 ## Nitro