docs: add docs for the key-value resource adapter

AdminForth/1735/kv-adapters-and-storage-s3-com

Author: yaroslav8765

adminforth/documentation/docs/tutorial/06-Adapters/07-key-value-adapters.md

@@ -11,7 +11,7 @@ Key-value adapters are used to store data in a key-value format. They provide a
 ## RAM Adapter
 
 ```bash
-pnpm i @adminforth/key-value-adapter-ram
+pnpm add @adminforth/key-value-adapter-ram
 ```
 
 The RAM adapter is a simple in-memory key-value store. It keeps data in process memory, so it is not suitable for multi-process deployments because each process would have its own isolated store. In that case you need a centralized KV adapter such as Redis.
@@ -27,7 +27,7 @@ Cons:
 ## Redis Adapter
 
 ```bash
-pnpm i @adminforth/key-value-adapter-redis
+pnpm add @adminforth/key-value-adapter-redis
 ```
 
 Redis uses in-memory storage with $O(1)$ get complexity. It is a great fit for lightweight workloads that fit in RAM, and it also works well for multi-process or replica-based installations as a centralized store. If persistence across restarts is important, configure Redis persistence separately.
@@ -45,7 +45,7 @@ adapter.set('test-key', 'test-value', 120);
 ## LevelDB Adapter
 
 ```bash
-pnpm i @adminforth/key-value-adapter-leveldb
+pnpm add @adminforth/key-value-adapter-leveldb
 ```
 
 LevelDB uses disk storage with $O(\log n)$ get complexity. It is a good fit for large or persistent KV datasets that still require fast lookups but do not efficiently fit in RAM. This is a single-process adapter only, so multiple admin processes should not point to the same LevelDB directory.
@@ -60,4 +60,99 @@ const adapter = new LevelDBKeyValueAdapter({
 });
 
 adapter.set('test-key', 'test-value', 120);
+```
+
+## Resource-based adapter
+```bash
+pnpm add @adminforth/key-value-adapter-resource
+```
+
+Resource adapter uses adminforth resource to store key/value pairs.
+
+### Setup
+
+1) Add schema in `./schema.prisma` file
+
+```
+model key_values {
+  key String @id
+  value String
+  collection String?
+}
+```
+
+2) Apply migration
+```bash
+pnpm makemigration --name add-adminforth-key-value-tables ; pnpm migrate:local
+```
+
+3) Create resource
+
+```ts title="./resources/key_value_resource.ts"
+import AdminForth, { AdminForthDataTypes } from 'adminforth';
+import type { AdminForthResourceInput, AdminUser } from 'adminforth';
+
+async function allowedForSuperAdmins({ adminUser }: { adminUser: AdminUser }): Promise<boolean> {
+  return adminUser.dbUser.role === 'superadmin';
+}
+
+export default {
+  dataSource: 'maindb',
+  table: 'key_values',
+  resourceId: 'key_values',
+  label: 'Key values',
+  columns: [
+    {
+      name: 'key',
+      primaryKey: true,
+      type: AdminForthDataTypes.STRING,
+    },
+    {
+      name: 'value',
+      type: AdminForthDataTypes.STRING,
+    },
+    {
+      name: 'collection',
+      type: AdminForthDataTypes.STRING,
+    }
+  ],
+  options: {
+    allowedActions: {
+      list: allowedForSuperAdmins,
+      show: allowedForSuperAdmins,
+      create: false,
+      edit: false,
+      delete: false,
+    },
+  },
+} as AdminForthResourceInput;
+```
+
+4) Register resource
+
+```ts title="./index.ts"
+import key_value_resource from './resources/key_value_resource.js';
+
+export const admin = new AdminForth({
+  ...
+  resources: [
+    ...
+    key_value_resource,
+  ],
+  ...
+});
+
+```
+
+5) Create instance of adapter
+
+```ts
+import ResourceKeyValueAdapter from '@adminforth/key-value-adapter-resource'
+
+const adapter = new ResourceKeyValueAdapter({
+  resourceId: 'key_values',
+  keyField: 'key',
+  valueField: 'value',
+  collectionField: 'collection',
+})
 ```