docs: add docs for mutation-property-order eslint rule (#9271)

Author: espada-edalex

docs/eslint/eslint-plugin-query.md

@@ -99,3 +99,4 @@ Alternatively, add `@tanstack/query` to the plugins section, and configure the r
 - [@tanstack/query/no-unstable-deps](../no-unstable-deps.md)
 - [@tanstack/query/infinite-query-property-order](../infinite-query-property-order.md)
 - [@tanstack/query/no-void-query-fn](../no-void-query-fn.md)
+- [@tanstack/query/mutation-property-order](../mutation-property-order.md)

docs/eslint/mutation-property-order.md

@@ -0,0 +1,73 @@
+---
+id: mutation-property-order
+title: Ensure correct order of inference-sensitive properties in useMutation()
+---
+
+For the following functions, the property order of the passed in object matters due to type inference:
+
+- `useMutation()`
+
+The correct property order is as follows:
+
+- `onMutate`
+- `onError`
+- `onSettled`
+
+All other properties are insensitive to the order as they do not depend on type inference.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```tsx
+/* eslint "@tanstack/query/mutation-property-order": "warn" */
+import { useMutation } from '@tanstack/react-query'
+
+const mutation = useMutation({
+  mutationFn: () => Promise.resolve('success'),
+  onSettled: () => {
+    results.push('onSettled-promise')
+    return Promise.resolve('also-ignored') // Promise<string> (should be ignored)
+  },
+  onMutate: async () => {
+    results.push('onMutate-async')
+    await sleep(1)
+    return { backup: 'async-data' }
+  },
+  onError: async () => {
+    results.push('onError-async-start')
+    await sleep(1)
+    results.push('onError-async-end')
+  },
+})
+```
+
+Examples of **correct** code for this rule:
+
+```tsx
+/* eslint "@tanstack/query/mutation-property-order": "warn" */
+import { useMutation } from '@tanstack/react-query'
+
+const mutation = useMutation({
+  mutationFn: () => Promise.resolve('success'),
+  onMutate: async () => {
+    results.push('onMutate-async')
+    await sleep(1)
+    return { backup: 'async-data' }
+  },
+  onError: async () => {
+    results.push('onError-async-start')
+    await sleep(1)
+    results.push('onError-async-end')
+  },
+  onSettled: () => {
+    results.push('onSettled-promise')
+    return Promise.resolve('also-ignored') // Promise<string> (should be ignored)
+  },
+})
+```
+
+## Attributes
+
+- [x] ✅ Recommended
+- [x] 🔧 Fixable