fix(doc): Cleanup of how to install python deps

Documentation/how-to-build.rst

@@ -73,29 +73,34 @@ Dependencies
 
 * One of three CRC packages are required. Pick one:
 
-  - for all OS's
+  - Ubuntu / Debian / macOS
 
     .. code-block:: shell-session
 
         pip3 install --user crc16
 
+or
+
     .. code-block:: shell-session
 
         pip3 install --user crcmod
 
+  - Arch
+
     .. code-block:: shell-session
 
-        pip3 install --user crcmod
+       pacman -S python-crc16
 
 * **python3-pillow**: Python Image Library
        .. code-block:: shell-session
+
             pip3 install --user pillow
 
   - Arch
 
     .. code-block:: shell-session
 
-       pacman -S python-crc16 python-pillow
+       pacman -S python-pillow
 
 .. _ARM's GNU toolchain: https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads