Add clarification about eslint-enable rule:

See #15662

docs/user-guide/configuring/rules.md

@@ -144,6 +144,8 @@ console.log('bar');
 /* eslint-enable no-alert, no-console */
 ```
 
+**Note:** `/* esline-enable */` without any specific rules will cause all errors to be re-enabled. You will have to re-specify the errors you wish to keep disabled.
+
 To disable rule warnings in an entire file, put a `/* eslint-disable */` block comment at the top of the file:
 
 ```js
@@ -160,6 +162,14 @@ You can also disable or enable specific rules for an entire file:
 alert('foo');
 ```
 
+To ensure that a rule is always applied (regardless of any future enable/disable lines):
+
+```js
+/* eslint no-alert: "off" */
+
+alert('foo');
+```
+
 To disable all rules on a specific line, use a line or block comment in one of the following formats:
 
 ```js