[Documentation] Inclusion of two-line install script for Unix (#155)

Closes #83
Authored-by: Ashish <ashish@pop-os.localdomain>

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README.md

@@ -103,6 +103,23 @@ You can install yt-dlp using one of the following methods:
 * Use pip+git: `python -m pip install --upgrade git+https://github.com/yt-dlp/yt-dlp.git@release`
 * Install master branch: `python -m pip install --upgrade git+https://github.com/yt-dlp/yt-dlp`
 
+UNIX users (Linux, macOS, BSD) can also install the [latest release](https://github.com/yt-dlp/yt-dlp/releases/latest) one of the following ways:
+
+```
+sudo curl -L https://github.com/yt-dlp/yt-dlp/releases/latest/download/yt-dlp -o /usr/local/bin/yt-dlp
+sudo chmod a+rx /usr/local/bin/yt-dlp
+```
+
+```
+sudo wget https://github.com/yt-dlp/yt-dlp/releases/latest/download/yt-dlp -O /usr/local/bin/yt-dlp
+sudo chmod a+rx /usr/local/bin/yt-dlp
+```
+
+```
+sudo aria2c https://github.com/yt-dlp/yt-dlp/releases/latest/download/yt-dlp -o /usr/local/bin/yt-dlp
+sudo chmod a+rx /usr/local/bin/yt-dlp
+```
+
 ### UPDATE
 Starting from version `2021.02.09`, you can use `yt-dlp -U` to update if you are using the provided release.
 If you are using `pip`, simply re-run the same command that was used to install the program.