docs: document DEB/RPM installation

Covers the amd64v3 vs amd64 choice — both packages declare Architecture:
amd64, so the file name is the only way to tell them apart — and the fact
that the packaged systemd service stays inactive until /etc/gost/gost.yml
is created.

README.md

@@ -54,6 +54,22 @@ GOST作为隧道有三种主要使用方式。
 
 [https://github.com/go-gost/gost/releases](https://github.com/go-gost/gost/releases)
 
+### 系统包（DEB/RPM）
+
+从 [Releases](https://github.com/go-gost/gost/releases) 下载对应架构的安装包（`amd64`、`amd64v3`、`arm64`）：
+
+```bash
+# Debian/Ubuntu
+sudo apt install ./gost_<version>_linux_amd64.deb
+
+# RHEL/Fedora
+sudo dnf install ./gost_<version>_linux_amd64.rpm
+```
+
+`amd64v3` 包需要支持 AVX2 的 CPU（x86-64-v3），否则请使用 `amd64`。
+
+安装包附带 systemd 服务，但不会自动启用：先创建 `/etc/gost/gost.yml`（示例见 `/usr/share/doc/gost/examples/gost.yml`），再执行 `sudo systemctl enable --now gost`。未提供配置文件时该服务会被跳过，而不是报错。
+
 ### 安装脚本
 
 ```bash

README_en.md

@@ -54,6 +54,22 @@ Use tunnel and intranet penetration to expose local services behind NAT or firew
 
 [https://github.com/go-gost/gost/releases](https://github.com/go-gost/gost/releases)
 
+### Packages (DEB/RPM)
+
+Download the package for your architecture from the [releases page](https://github.com/go-gost/gost/releases) (`amd64`, `amd64v3`, `arm64`):
+
+```bash
+# Debian/Ubuntu
+sudo apt install ./gost_<version>_linux_amd64.deb
+
+# RHEL/Fedora
+sudo dnf install ./gost_<version>_linux_amd64.rpm
+```
+
+The `amd64v3` package requires an AVX2-capable CPU (x86-64-v3); use `amd64` otherwise.
+
+The packages ship a systemd service, but it is not enabled automatically: create `/etc/gost/gost.yml` first (see `/usr/share/doc/gost/examples/gost.yml`), then run `sudo systemctl enable --now gost`. Without a config file the service is skipped rather than failing.
+
 ### install script
 
 ```bash