chore: move image assets under .github (#732)

Signed-off-by: Chris Gianelloni <[email protected]>

Author: wolf31o2

.dockerignore

@@ -1,5 +1,4 @@
 .git/
 .github/
-assets/
 Dockerfile
 README.md

assets/gOuroboros-illustration.png renamed to .github/assets/gOuroboros-illustration.png

@@ -1,5 +1,5 @@
 <div align="center">
-  <img src="./assets/gOuroboros-logo-with-text-horizontal.png" alt="gOurobros Logo" width="640">
+  <img src="./.github/assets/gOuroboros-logo-with-text-horizontal.png" alt="gOurobros Logo" width="640">
   <br>
   <img alt="GitHub" src="https://img.shields.io/github/license/blinklabs-io/gouroboros">
   <a href="https://goreportcard.com/report/github.com/blinklabs-io/gouroboros"><img src="https://goreportcard.com/badge/github.com/blinklabs-io/gouroboros" alt="Go Report Card"></a>