Docs/reference (#323)

Document operator command-line options and environment variables.

docs/reference/command_line_and_environment.md

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+## Command-line options
+
+The following command-line options are supported for the operator:
+
+* **-kubeconfig**
+  the path to the kubeconfig file. Usually named config, it contains
+  authorization information as well as the URL of the Kubernetes master.
+
+* **-outofcluster**
+  run the operator on a client machine, as opposed to a within the cluster.
+  When running in this mode, the operator cannot connect to databases inside
+  the cluster, as well as call URLs of in-cluster objects (i.e. teams api
+  server). Mostly useful for debugging, it also requires setting the
+  `OPERATOR_NAMESPACE` environment variable for the operator own namespace.
+
+* **-nodatabaseaccess**
+  disable database access from the operator. Equivalent to the
+  `enable_database_access` set to off and can be overridden by the
+  aforementioned operator configuration option.
+
+* **-noteamsapi**
+  disable access to the teams API. Equivalent to the `enable_teams_api` set to
+  off can can be overridden by the aforementioned operator configuration
+  option.
+
+In addition to that, standard [glog
+flags](https://godoc.org/github.com/golang/glog) are also supported. For
+instance, one may want to add `-alsologtostderr` and `-v=8` to debug the
+operator REST calls.
+
+## Environment variables
+
+The following environment variables are accepted by the operator:
+
+* **CONFIG_MAP_NAME**
+  name of the config map where the operator should look for its configuration.
+  Must be present.
+
+* **OPERATOR_NAMESPACE**
+  name of the namespace the operator runs it. Overrides autodetection by the
+  operator itself.
+
+* **WATCHED_NAMESPACE**
+  the name of the namespace the operator watches. Special '*' character denotes
+  all namespaces. Empty value defaults to the operator namespace. Overrides the
+  `watched_namespace` operator parameter.
+
+* **SCALYR_API_KEY**
+  the value of the Scalyr API key to supply to the pods. Overrides the
+  `scalyr_api_key` operator parameter.