docs(core): add how to provide annotation properties

Signed-off-by: Emilien Escalle <[email protected]>

Author: neilime

packages/core/README.md

@@ -170,6 +170,22 @@ export interface AnnotationProperties {
 }
 ```
 
+Example:
+
+```js
+core.error(
+  'This is a bad error seen in file.',
+  {
+    title: "Unexpected Error",
+    file: "path/to/errored-file.js",
+    startLine: 1,
+    endLine: 2,
+    startColumn: 1,
+    endColumn: 10,
+  }
+)
+```
+
 #### Styling output
 
 Colored output is supported in the Action logs via standard [ANSI escape codes](https://en.wikipedia.org/wiki/ANSI_escape_code). 3/4 bit, 8 bit and 24 bit colors are all supported.
@@ -483,4 +499,4 @@ core.summary.emptyBuffer()
 
 // Writes text in the buffer to the summary buffer file and empties the buffer, optionally overwriting all existing content in the summary file with buffer contents. Defaults to false.
 core.summary.write({overwrite: true})
-```
+```