feat(assignees): add 6 new options to avoid stale for assignees (#327)

* feat(assignees): add new option to avoid stale for assignees

closes #271

* test: add more coverage

* docs: fix readme format issue

* docs: reorder and enhance typo

* docs(contributing): add more information about the npm scripts

__tests__/functions/generate-iissue.ts

@@ -0,0 +1,19 @@
+import {IIssue} from '../../src/interfaces/issue';
+
+export function generateIIssue(
+  partialIssue?: Readonly<Partial<IIssue>>
+): IIssue {
+  return {
+    milestone: undefined,
+    assignees: [],
+    labels: [],
+    created_at: new Date().toISOString(),
+    updated_at: new Date().toISOString(),
+    number: Math.round(Math.random() * 5000),
+    pull_request: null,
+    title: 'dummy-title',
+    locked: false,
+    state: 'dummy-state',
+    ...partialIssue
+  };
+}