Release v0.8.0 — Portainer-first install, in-app guide

- Install from Portainer with no command line: paste the compose, set a
  folder and a password, deploy. Inspector creates its own config and
  detects Docker socket permissions by itself.
- Illustrated how-to guide inside the app (Help tab) and in the repo.
- Containers added in the UI are watched right away, no restart.
- maintenance_window switch on the container form.
- README with logo and screenshots; INSTALL rewritten for Portainer.

Dockerfile

@@ -19,9 +19,14 @@ ARG INSPECTOR_UID=1000
 ARG INSPECTOR_GID=1000
 RUN groupadd --gid ${INSPECTOR_GID} inspector \
  && useradd  --uid ${INSPECTOR_UID} --gid inspector --home-dir /app --shell /usr/sbin/nologin inspector \
- && mkdir -p /app/logs /app/data \
- && chown -R inspector:inspector /app/logs /app/data
+ && mkdir -p /app/config /app/logs /app/data \
+ && chown -R inspector:inspector /app/config /app/logs /app/data
 
-USER inspector
+COPY docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh
+RUN chmod 755 /usr/local/bin/docker-entrypoint.sh
 
-CMD ["python", "-m", "inspector.main", "--config", "/app/config.yml"]
+# Starts as root only to detect the Docker socket's group and fix mounted
+# folder ownership, then drops to PUID:PGID (default 1000:1000).
+# See docker-entrypoint.sh.
+ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]
+CMD ["python", "-m", "inspector.main"]