Install mkdocs as non-root

Dockerfile

@@ -32,10 +32,7 @@ USER root
 # Install VCS tools to support https://pip.readthedocs.io/en/1.1/requirements.html#requirements-file-format
 RUN yum install -y rh-python36-python-pip git svn && \
     yum clean all && \
-    /opt/rh/rh-python36/root/usr/bin/pip install --cache-dir /root --upgrade pip setuptools wheel && \
-    /opt/rh/rh-python36/root/bin/pip install --cache-dir /opt/app-root/.cache --prefix /opt/app-root \
-        mkdocs==${MKDOCS_VERSION} \
-        mkdocs-material==${MATERIAL_VERSION}
+    /opt/rh/rh-python36/root/usr/bin/pip install --cache-dir /root --upgrade pip setuptools wheel
 
 # Move the original assemble script to another file
 # and copy our custom assemble script.
@@ -44,3 +41,7 @@ COPY assemble /usr/libexec/s2i/
 
 # Switch back to the default user.
 USER 1001
+
+RUN /opt/rh/rh-python36/root/bin/pip install --cache-dir /opt/app-root/.cache --prefix /opt/app-root \
+    mkdocs==${MKDOCS_VERSION} \
+    mkdocs-material==${MATERIAL_VERSION}