Docs: add class fields in no-multi-assign documentation (refs #14857)

docs/rules/no-multi-assign.md

@@ -26,12 +26,19 @@ const foo = bar = "baz";
 let a =
     b =
     c;
+
+class Foo {
+    a = b = 10;
+}
+
+a = b = "quux";
 ```
 
 Examples of **correct** code for this rule:
 
 ```js
 /*eslint no-multi-assign: "error"*/
+
 var a = 5;
 var b = 5;
 var c = 5;
@@ -41,13 +48,21 @@ const bar = "baz";
 
 let a = c;
 let b = c;
+
+class Foo {
+    a = 10;
+    b = 10;
+}
+
+a = "quux";
+b = "quux";
 ```
 
 ## Options
 
 This rule has an object option:
 
-* `"ignoreNonDeclaration"`: When set to `true`, the rule allows chains that don't include initializing a variable in a declaration. Default is `false`.
+* `"ignoreNonDeclaration"`: When set to `true`, the rule allows chains that don't include initializing a variable in a declaration or initializing a class field. Default is `false`.
 
 ### ignoreNonDeclaration
 
@@ -73,6 +88,10 @@ Examples of **incorrect** code for the `{ "ignoreNonDeclaration": true }` option
 let a = b = "baz";
 
 const foo = bar = 1;
+
+class Foo {
+    a = b = 10;
+}
 ```
 
 ## Related Rules