[ADF-2463] Moved core components to subfolder (#3062)

docs/core/highlight-transform.service.md

@@ -0,0 +1,46 @@
+---
+Added: v2.0.0
+Status: Active
+---
+# Highlight Transform service
+
+Adds HTML to a string to highlight chosen sections.
+
+## Methods
+
+-   `highlight(text: string, search: string, wrapperClass: string = 'highlight'): HightlightTransformResult`  
+    Searches for `search` string(s) within `text` and highlights all occurrences.  
+    -   `text` - Text to search within
+    -   `search` - Text pattern to search for
+    -   `wrapperClass` - CSS class used to provide highlighting style
+
+## Details
+
+A typical use case for this service is to display the results from a search engine.
+An excerpt of a retrieved document can be shown with the matching search terms
+highlighted to indicate where they were found.
+
+The service works by adding HTML <span> elements around all sections of text
+that match the `search` string. You can specify multiple search strings at once by
+separating them with spaces, so passing "Apple Banana Cherry" in `search` will
+highlight any of those words individually. The <span> element includes a
+`class` attribute which defaults to "highlight" but you can pass any class name
+you like using the `wrapperClass` parameter.
+
+The resulting text with HTML highlighting is returned within a `HightlightTransformResult`
+object:
+
+```ts
+interface HightlightTransformResult {
+    text: string;
+    changed: boolean;
+}
+```
+
+The `changed` flag will be false if the search string was not found (ie, no highlighting
+took place) and true otherwise.
+
+## See also
+
+-   [Text highlight pipe](text-highlight.pipe.md)
+-   [Highlight directive](highlight.directive.md)