docs: 添加国内Linux环境安装配置文档

添加详细文档说明在国内网络环境下配置Linux系统，包括：
1. 使用chsrc更换系统源和软件源
2. 通过清华镜像安装Homebrew/Linuxbrew
3. 使用Homebrew安装fnm管理node环境

Author: mudssky

linux/国内linux环境安装.md

@@ -0,0 +1,59 @@
+## 1.换源
+
+使用chsrc项目可以换各种系统源和软件源
+
+https://github.com/RubyMetric/chsrc
+
+```
+curl -LO https://gitee.com/RubyMetric/chsrc/releases/download/pre/chsrc_latest-1_amd64.deb
+sudo apt install ./chsrc_latest-1_amd64.deb
+```
+
+
+
+
+
+## 2.安装homebrew
+
+可以用清华的homebrew源安装
+
+https://mirrors.tuna.tsinghua.edu.cn/help/homebrew/
+
+在终端输入以下几行命令设置环境变量：
+
+```
+export HOMEBREW_BREW_GIT_REMOTE="https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/brew.git"
+export HOMEBREW_CORE_GIT_REMOTE="https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git"
+export HOMEBREW_INSTALL_FROM_API=1
+# export HOMEBREW_API_DOMAIN
+# export HOMEBREW_BOTTLE_DOMAIN
+# export HOMEBREW_PIP_INDEX_URL
+```
+
+在终端运行以下命令以安装 Homebrew / Linuxbrew
+
+```
+# 从镜像下载安装脚本并安装 Homebrew / Linuxbrew
+git clone --depth=1 https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/install.git brew-install
+/bin/bash brew-install/install.sh
+rm -rf brew-install
+
+# 也可从 GitHub 获取官方安装脚本安装 Homebrew / Linuxbrew
+/bin/bash -c "$(curl -fsSL https://github.com/Homebrew/install/raw/master/install.sh)"
+```
+
+## 3.node环境安装
+
+使用homebrew 安装fnm
+
+```
+brew install fnm
+# 安装后需要peizhishell
+# 在 ~/.bashrc中添加下面这行
+# eval "$(fnm env --use-on-cd --shell bash)"
+# 之后 source ~/.bashrc
+fnm install 22
+fnm use 22
+
+```
+