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__/constants/default-processor-options.ts

@@ -32,5 +32,11 @@ export const DefaultProcessorOptions: IIssuesProcessorOptions = Object.freeze({
   exemptPrMilestones: '',
   exemptAllMilestones: false,
   exemptAllIssueMilestones: undefined,
-  exemptAllPrMilestones: undefined
+  exemptAllPrMilestones: undefined,
+  exemptAssignees: '',
+  exemptIssueAssignees: '',
+  exemptPrAssignees: '',
+  exemptAllAssignees: false,
+  exemptAllIssueAssignees: undefined,
+  exemptAllPrAssignees: undefined
 });