chore(docs): replace email with SO and GitHub links (#5583)

docs/app/@theme/components/header/header.component.html

@@ -16,10 +16,6 @@
 </div>
 <div class="section right">
 
-  <ng-container *ngIf="!isDocs">
-    Need some help? Let us know! <a (click)="trackEmailClick()" href="mailto:contact@akveo.com">contact@akveo.com</a>
-  </ng-container>
-
   <iframe *ngIf="isDocs"
           class="stars"
           src="https://ghbtns.com/github-btn.html?user=akveo&repo=ngx-admin&type=star&count=true"

docs/app/pages/docs/landing-docs.component.html

@@ -12,7 +12,10 @@
 
     <div class="contact-us">
       <h2>Need some help or found an issue?</h2>
-      <p>Contact us at <a href="mailto:contact@akveo.com">contact@akveo.com</a></p>
+      <p>
+        Ask on <a href="https://stackoverflow.com/questions/ask">Stack Overflow</a> with tag `ngx-admin` or
+        post an issue on <a href="https://github.com/akveo/ngx-admin/issues/new">GitHub</a>.
+      </p>
     </div>
   </nb-layout-column>
   <nb-layout-footer>

docs/articles/index.md

@@ -47,4 +47,4 @@ And many more!
 This documentation assumes that you are already familiar with JavaScript/TypeScript, Angular, CSS and Bootstrap.
 
 ## Have questions?
-Didn't find something here? Look through the <a href="https://github.com/akveo/ngx-admin/issues" target="_blank">issues</a> or simply drop us a line at <a href="mailto:contact@akveo.com">contact@akveo.com</a>.
+Didn't find something here? Look through the <a href="https://github.com/akveo/ngx-admin/issues" target="_blank">issues</a> or ask on <a href="https://stackoverflow.com/questions/ask" target="_blank">Stack Overflow</a>.