Refine ddev config

.ddev/commands/solr/README.txt

@@ -0,0 +1,24 @@
+Scripts in this directory will be executed inside the solr
+container (if it exists, of course). This is just an example,
+but any named service can have a directory with commands.
+
+Note that /mnt/ddev_config must be mounted into the 3rd-party service
+with a stanza like this in the docker-compose.solr.yaml:
+
+    volumes:
+      - type: "bind"
+        source: "."
+        target: "/mnt/ddev_config"
+
+
+A number of environment variables are supplied to the scripts, including:
+
+DDEV_DOCROOT: Relative path from approot to docroot
+DDEV_HOSTNAME: Comma-separated list of FQDN hostnames
+DDEV_PHP_VERSION
+DDEV_WEBSERVER_TYPE: nginx-fpm, apache-fpm, apache-cgi
+DDEV_PROJECT_TYPE: drupal8, typo3, backdrop, wordpress, etc.
+DDEV_ROUTER_HTTP_PORT: Router port for http
+DDEV_ROUTER_HTTPS_PORT: Router port for https
+
+More environment variables may be available, see https://github.com/drud/ddev/blob/52c7915dee41d4846f9f619520b726994c0372c5/pkg/ddevapp/ddevapp.go#L1006-L1030