adding cp to the image

Author: afarzat-ed

Diff for: devdocs.md

@@ -3,6 +3,6 @@
 * Update the version on projects/plotly/package.json
 * `ng test --codeCoverage=true --progress=true --watch=false`
 * `ng build plotly --prod`
-* `cp README.md dist/plotly`
+* `cp README.md angular-plotly.png dist/plotly`
 * `npm publish dist/plotly`
 * `git tag -a <version> -m <version>`