Create rule docs for toggle based on PR feedback

packages/eslint-plugin/docs/rules/toggle.md

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+# Toggle (`opticks/toggle`)
+
+Detects stale code from expired Opticks experiments, and other common mistakes related to toggles.
+
+## Rule Details
+
+This rule aims to to guide users of Opticks to correct use of the library, as well as indicate which experiments in the code should be considered for clean up.
+
+### Options
+
+This rule expects a configuration to be present in order to detect experiments to be cleaned up.
+
+```json
+{
+    "settings": {
+        "opticks": {
+            "experiments": {
+                "foo": "a", 
+                "bar": null, 
+                "baz": "b"
+            }
+        }
+    }
+}
+```
+
+By convention, the value of an experiment of `null` means the experiment is still running, and a string value such as `a` or `b` means it's concluded to the side specified and the other sides can be cleaned up.
+
+## When Not To Use It
+
+If you don't use Opticks.