Fix - use `[routerLink]` in `posts` and `series` - not click event

- initially I have set the app to use `[routerLink]` but it got changed to on `(click)` event
- which is not only redundant for `a` elements but also causes the link to not be recognized properly in the browser and
- the context menu doesn't give the option of `open link in a new tab`

**Describe the solution you'd like**
- use `[routerLink]` a initially intend de in both `series` and `posts`