revise Installation instruction

README.md

@@ -2,7 +2,7 @@
 [![ci][ci-badge]][ci-link] [![chat][chat-badge]][chat-link]
 
 [Signal Messenger] client for terminal.
-
+pkg install net-im/gurk-rs
 ![screenshot](screenshot.png)
 
 # Installation
@@ -30,7 +30,14 @@ cargo install --git https://github.com/boxdot/gurk-rs gurk
 
 ## Arch Linux
 
+```shell
+pacman -S gurk
+```
+(as root)
 - Official repository, tagged releases: [`gurk`](https://archlinux.org/packages/extra/x86_64/gurk)
+```shell
+yay -S gurk
+```
 - AUR source build from Git HEAD: [`gurk-git`](https://aur.archlinux.org/packages/gurk-bin)
 
 ## Nix/NixOS
@@ -47,6 +54,19 @@ or system-wide:
 environment.systemPackages = with pkgs; [ gurk-rs ];
 ```
 
+# Freebsd
+#### (as root)
+```shell
+pkg install net-im/gurk-rs
+```
+- pkg repositories
+
+
+```shell
+cd /usr/ports/net-im/gurk-rs
+make install clean
+```
+- ports tree
 # Usage
 
 Run