Documentation: replace git protocol with https

git protocol will be retired by GitHub soon.
Replace it with supported https instead.

README.md

@@ -59,7 +59,7 @@ methods.
 Clone the `void-packages` git repository and install the bootstrap packages:
 
 ```
-$ git clone git://github.com/void-linux/void-packages.git
+$ git clone https://github.com/void-linux/void-packages.git
 $ cd void-packages
 $ ./xbps-src binary-bootstrap
 ```
@@ -441,7 +441,7 @@ try other [chroot methods](#chroot-methods).
 
 Clone the `void-packages` git repository:
 
-    $ git clone git://github.com/void-linux/void-packages
+    $ git clone https://github.com/void-linux/void-packages.git
 
 and `xbps-src` should be fully functional; just start the `bootstrap` process, i.e: