[ADF-4152] Updated folder structure of core docs (#4415)

* [ADF-4152] Moved core library docs into subfolders

* [ADF-4152] Moved core library docs into subfolders

* [ADF-4152] Manual fixes to core doc file links

* [ADF-4152] Further automatic + manual link tidying

docs/core/services/thumbnail.service.md

@@ -0,0 +1,72 @@
+---
+Title: Thumbnail service
+Added: v2.0.0
+Status: Active
+Last reviewed: 2018-11-13
+---
+
+# [Thumbnail service](../../../lib/core/services/thumbnail.service.ts "Defined in thumbnail.service.ts")
+
+Retrieves an SVG thumbnail image to represent a document type.
+
+## Class members
+
+### Methods
+
+-   **getDefaultMimeTypeIcon**(): `string`<br/>
+    Gets a "miscellaneous" thumbnail URL for types with no other icon defined.
+    -   **Returns** `string` - URL string
+-   **getDocumentThumbnailUrl**(node: `any`): `string`<br/>
+    Gets a thumbnail URL for the given document node.
+    -   _node:_ `any`  - [Node](https://github.com/Alfresco/alfresco-js-api/blob/development/src/api/content-rest-api/docs/Node.md) to get URL for.
+    -   **Returns** `string` - URL string
+-   **getMimeTypeIcon**(mimeType: `string`): `string`<br/>
+    Gets a thumbnail URL for a MIME type.
+    -   _mimeType:_ `string`  - MIME type for the thumbnail
+    -   **Returns** `string` - URL string
+
+## Details
+
+The service can locate a thumbnail icon (in SVG format) for either
+a document node or a MIME type. The default mapping between types
+and icons is shown in the table below:
+
+| Document | Icon | Types |
+| -------- | ---- | ----- |
+| Compressed archive | ![Archive thumbnail](../../docassets/images/ft_ic_archive.png) | 'application/x-compressed', 'application/x-zip-compressed', 'application/zip' |
+| Text | ![Text thumbnail](../../docassets/images/ft_ic_document.png) | 'text/plain', 'application/json', 'application/x-javascript', 'application/vnd.apple.pages' |
+| Bitmap/raster image | ![Bitmap thumbnail](../../docassets/images/ft_ic_raster_image.png) | 'image/png', 'image/jpeg', 'image/gif' |
+| MP4 video | ![MP4 thumbnail](../../docassets/images/ft_ic_video.png) | 'video/mp4' |
+| SVG vector image | ![SVG thumbnail](../../docassets/images/ft_ic_vector_image.png) | 'image/svg+xml' |
+| HTML file | ![HTML thumbnail](../../docassets/images/ft_ic_website.png) | 'text/html' |
+| PDF file | ![PDF thumbnail](../../docassets/images/ft_ic_pdf.png) | 'application/pdf' |
+| Folder | ![Folder thumbnail](../../docassets/images/ft_ic_folder.png) |  |
+| Disabled folder | ![Disabled folder thumbnail](../../docassets/images/ft_ic_folder_disable.png) |  |
+| Excel spreadsheet | ![Spreadsheet thumbnail](../../docassets/images/ft_ic_ms_excel.png) | 'application/vnd.ms-excel', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'application/vnd.openxmlformats-officedocument.spreadsheetml.template' |
+| PowerPoint slideshow | ![PowerPoint thumbnail](../../docassets/images/ft_ic_ms_powerpoint.png) | 'application/vnd.ms-powerpoint', 'application/vnd.openxmlformats-officedocument.presentationml.presentation', 'application/vnd.openxmlformats-officedocument.presentationml.template', 'application/vnd.openxmlformats-officedocument.presentationml.slideshow' |
+| Word document | ![Word thumbnail](../../docassets/images/ft_ic_ms_word.png) | 'application/msword', 'application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'application/vnd.openxmlformats-officedocument.wordprocessingml.template' |
+| Keynote presentation | ![Keynote thumbnail](../../docassets/images/ft_ic_presentation.png) | 'application/vnd.apple.keynote' |
+| Numbers spreadsheet | ![Numbers thumbnail](../../docassets/images/ft_ic_spreadsheet.png) | 'application/vnd.apple.numbers' |
+
+### Mat-icon
+
+All the ADF icons for MIME types are now registered into the [`MatIconRegistry`](https://material.angular.io/components/icon/api), so you can use all
+the icons via the &lt;mat-icon> tag:
+
+```javascript
+import { ThumbnailService } from '@alfresco/adf-core';
+
+constructor(public thumbnailService: ThumbnailService) {
+}‍‍‍‍‍‍‍‍
+```
+
+```html
+MP4 <mat-icon svgIcon="video/mp4"></mat-icon>
+PDF <mat-icon svgIcon="application/pdf"></mat-icon>
+GIF <mat-icon svgIcon="image/gif"></mat-icon>
+.....
+```
+
+## See also
+
+-   [Mime type icon pipe](../pipes/mime-type-icon.pipe.md)