docs: update dockerfile for new version package

Signed-off-by: Evan Hazlett <ejhazlett@gmail.com>

docs/Dockerfile

@@ -7,7 +7,7 @@ COPY . /src
 # Reset the /docs dir so we can replace the theme meta with the new repo's git info
 RUN git reset --hard
 
-RUN grep VERSION /src/version.go  | sed 's/.*"\(.*\)".*/\1/' > /docs/VERSION
+RUN grep "VERSION =" /src/version/version.go  | sed 's/.*"\(.*\)".*/\1/' > /docs/VERSION
 COPY docs/* /docs/sources/machine/
 COPY docs/mkdocs.yml /docs/mkdocs-machine.yml