Update docs image.

docs.Dockerfile

@@ -1,5 +1,5 @@
 # Generate the HTML output.
-FROM markstory/cakephp-docs-builder as builder
+FROM ghcr.io/cakephp/docs-builder as builder
 
 # Copy entire repo in with .git so we can build all versions in one image.
 COPY docs /data/docs
@@ -8,7 +8,7 @@ RUN cd /data/docs-builder \
   && make website LANGS="en es fr ja pt ru" SOURCE=/data/docs DEST=/data/website/
 
 # Build a small nginx container with just the static site in it.
-FROM markstory/cakephp-docs-builder:runtime as runtime
+FROM ghcr.io/cakephp/docs-builder:runtime as runtime
 
 # Configure search index script
 ENV LANGS="en es fr ja pt ru"