docs: update Install guide (#24)

* docs: update installation guide

* docs: remove api text

docs/_sidebar.md

@@ -31,8 +31,8 @@
 - [Fetch Supported Calendars](./api/fetchSupportedCalendars.md)
 - [Fetch Supported Currencies](./api/fetchSupportedCurrencies.md)
 - [Fetch Converted Time](./api/fetchConvertedTime.md)
-- [Fetch Time Difference API](./api/fetchTimeDifference.md)
-- [Calculate Duration API](./api/calculateDurationAPI.md)
+- [Fetch Time Difference](./api/fetchTimeDifference.md)
+- [Calculate Duration](./api/calculateDurationAPI.md)
 - [Format Date in Timezone](./api/formatDateInTimezoneAPI.md)
 - [Format Date for locale](./api/formatDateInLocale.md)
 - [Fetch Count Down To Event](./api/getCountdownToEvent.md)

docs/guide/installation.md

@@ -2,14 +2,16 @@
 
 First, you need to download node.js 20+ [Download Node.js](https://nodejs.org/en/download/).
 
-Then You can install the package via npm or yarn.
+You can install `world-clockify` using any of these popular package managers:
 
-```shell
+```bash
 npm install world-clockify
 ```
 
-or yarn
-
 ```bash
 yarn add world-clockify
 ```
+
+```bash
+pnpm add world-clockify
+```