Add: GnuPG Guide (#25060)

* Add: GnuPG Guide

* Update index.md

* Update index.md

* Update index.md

* fixed title

guide/english/gnupg/index.md

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+---
+title: GnuPG
+---
+
+__Gnu Privacy Guard (GnuPG)__ is a free software implementation of the [OpenPGP Standard](https://www.openpgp.org/about/standard/). Most people use GnuPG or GPG to encrypt and sign files and messages while some also use it for Secure Shell (SSH) authentication and signing their Git commits and tags.
+
+## Installation
+
+### Linux
+GnuPG is part of Debian. To install on Debian or its derivatives:
+```text
+sudo apt install gnupg
+```
+For non-Debian Linux distributions, consult the appropriate guide for the distro of your choice.
+
+### macOS
+To install GnuPG on a Mac, you can use [Homebrew](https://brew.sh):
+```text
+brew install gnupg
+```
+
+### Windows
+To install GnuPG on Windows, you can download the [Gpg4win Installer](https://gpg4win.org/download.html).
+
+## Generating keys
+Before you can start using GPG, you need to first generate a key pair. To do so, key in the command in your terminal or command prompt:
+```text
+gpg --gen-key
+```
+Follow the prompts by entering your name, email, and passphrase and you are done. Congratulations!
+
+## Resources
+- [GnuPG Manual](https://www.gnupg.org/documentation/manuals.html)