fix: Update README references

[Ramboio]

Some docs contain references to /wurstbrot/ private repo that are being automatically forwarded to /devsecopsmaturitymodel/ repo, probably due to renaming.

This PR updates those references to the project repo. All links and images still work as expected.

[Ramboio]

There is still one reference remaining, that is in sidenav-buttons.component.html
However, this do not seem to be used, nor it shows on the website. I'm not sure if it should be fixed, removed or left untouched, so I did the latter

[vbakke]

Thank you, @Ramboio. This was in my blind spot.

The SideNav button is in use in the side menu. It would be great if you could change that one as well, and I'll approve your pull request :)

[Ramboio]

@vbakke After forking the project and running locally I was able to see the button. On the project main page's demo it is not enabled. Now the last reference is fixed

[vbakke]

and then the linter kick in, with it's max line length.

Either add the new lines as it suggest, or put the URL as a variable in the component. :)

[github-actions]

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