Update README.md (nvim-lua#860)

Attempted fix for nvim-lua#859, provide reasonable Debian install instructions -- comment on GitHub issue with refinement.

Author: EvanCarroll

README.md

@@ -200,9 +200,14 @@ sudo apt install make gcc ripgrep unzip git neovim
 ```
 sudo apt update
 sudo apt install make gcc ripgrep unzip git
-echo "deb https://deb.debian.org/debian unstable main" | sudo tee -a /etc/apt/sources.list
-sudo apt update
-sudo apt install -t unstable neovim
+
+# Now we install nvim
+curl -LO https://github.com/neovim/neovim/releases/latest/download/nvim-linux64.tar.gz
+sudo rm -rf /opt/nvim
+sudo tar -C /opt -xzf nvim-linux64.tar.gz
+
+# make it available in /usr/local/bin, distro installs to /usr/bin
+sudo ln -sf /opt/nvim-linux64/bin/nvim /usr/local/bin/
 ```
 </details>
 <details><summary>Fedora Install Steps</summary>