docs: add example usage of conflicts

Author: amaanq

docs/src/creating-parsers/3-writing-the-grammar.md

@@ -291,6 +291,69 @@ This is where `prec.left` and `prec.right` come into use. We want to select the
 }
 ```
 
+## Using Conflicts
+
+Sometimes, conflicts are actually desirable. In our JavaScript grammar, expressions and patterns can create intentional ambiguity.
+A construct like `[x, y]` could be legitimately parsed as both an array literal (like in `let a = [x, y]`) or as a destructuring
+pattern (like in `let [x, y] = arr`).
+
+```js
+module.exports = grammar({
+  name: "javascript",
+
+  rules: {
+    expression: $ => choice(
+      $.identifier,
+      $.array,
+      $.pattern,
+    ),
+
+    array: $ => seq(
+      "[",
+      optional(seq(
+        $.expression, repeat(seq(",", $.expression))
+      )),
+      "]"
+    ),
+
+    array_pattern: $ => seq(
+      "[",
+      optional(seq(
+        $.pattern, repeat(seq(",", $.pattern))
+      )),
+      "]"
+    ),
+
+    pattern: $ => choice(
+      $.identifier,
+      $.array_pattern,
+    ),
+  },
+})
+```
+
+In such cases, we want the parser to explore both possibilities by explicitly declaring this ambiguity:
+
+```js
+{
+  name: "javascript",
+
+  conflicts: $ => [
+    [$.array, $.array_pattern],
+  ],
+
+  rules: {
+    // ...
+  },
+}
+```
+
+```admonish note
+The example is a bit contrived for the purpose of illustrating the usage of conflicts. The actual JavaScript grammar isn't
+structured like that, but this conflict is actually present in the
+[Tree-sitter JavaScript grammar](https://github.com/tree-sitter/tree-sitter-javascript/blob/108b2d4d17a04356a340aea809e4dd5b801eb40d/grammar.js#L100).
+```
+
 ## Hiding Rules
 
 You may have noticed in the above examples that some grammar rule name like `_expression` and `_type` began with an underscore.