docs: add docs

Author: baseballyama

README.md

@@ -269,6 +269,7 @@ These rules relate to possible syntax or logic errors in Svelte code:
 | [svelte/no-not-function-handler](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-not-function-handler/) | disallow use of not function in event handler | :star: |
 | [svelte/no-object-in-text-mustaches](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-object-in-text-mustaches/) | disallow objects in text mustache interpolation | :star: |
 | [svelte/no-shorthand-style-property-overrides](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-shorthand-style-property-overrides/) | disallow shorthand style properties that override related longhand properties | :star: |
+| [svelte/no-store-async](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-store-async.md) | disallow using async/await inside svelte stores | :star: |
 | [svelte/no-unknown-style-directive-property](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-unknown-style-directive-property/) | disallow unknown `style:property` | :star: |
 | [svelte/valid-compile](https://ota-meshi.github.io/eslint-plugin-svelte/rules/valid-compile/) | disallow warnings when compiling. | :star: |
 

docs/rules.md

@@ -22,6 +22,7 @@ These rules relate to possible syntax or logic errors in Svelte code:
 | [svelte/no-not-function-handler](./rules/no-not-function-handler.md) | disallow use of not function in event handler | :star: |
 | [svelte/no-object-in-text-mustaches](./rules/no-object-in-text-mustaches.md) | disallow objects in text mustache interpolation | :star: |
 | [svelte/no-shorthand-style-property-overrides](./rules/no-shorthand-style-property-overrides.md) | disallow shorthand style properties that override related longhand properties | :star: |
+| [svelte/no-store-async](./rules/no-store-async.md) | disallow using async/await inside svelte stores | :star: |
 | [svelte/no-unknown-style-directive-property](./rules/no-unknown-style-directive-property.md) | disallow unknown `style:property` | :star: |
 | [svelte/valid-compile](./rules/valid-compile.md) | disallow warnings when compiling. | :star: |
 

docs/rules/no-store-async.md

@@ -0,0 +1,57 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "svelte/no-store-async"
+description: "disallow using async/await inside svelte stores"
+since: "v3.1.0"
+---
+
+# svelte/no-store-async
+
+> disallow using async/await inside svelte stores
+
+- :gear: This rule is included in `"plugin:svelte/recommended"`.
+
+## :book: Rule Details
+
+This rule reports all uses of async/await inside svelte stores.
+Because it causes issues with the auto-unsubscribing features.
+
+<ESLintCodeBlock language="javascript">
+
+<!--eslint-skip-->
+
+```js
+/* eslint svelte/no-store-async: "error" */
+
+import { writable, readable, derived } from "svelte/store"
+
+/* ✓ GOOD */
+const w1 = writable(false, () => {})
+const r1 = readable(false, () => {})
+const d1 = derived(a1, ($a1) => {})
+
+/* ✗ BAD */
+const w2 = writable(false, async () => {})
+const r2 = readable(false, async () => {})
+const d2 = derived(a1, async ($a1) => {})
+```
+
+</ESLintCodeBlock>
+
+## :wrench: Options
+
+Nothing.
+
+## :books: Further Reading
+
+- [Svelte - Docs > 4. Prefix stores with $ to access their values / Store contract](https://svelte.dev/docs#component-format-script-4-prefix-stores-with-$-to-access-their-values-store-contract)
+
+## :rocket: Version
+
+This rule was introduced in eslint-plugin-svelte v3.1.0
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/src/rules/no-store-async.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/tests/src/rules/no-store-async.ts)