README: add download section

The *Firmware Selector* was built to simplify users finding suitable
images for their devices. Let's give it more visibility so unleashing
your home router becomes an easier thing.

As an alternative for more advanced user, provide the directl link to
the wiki download section.

Signed-off-by: Paul Spooren <mail@aparcar.org>
[ fix typo in commit description, add link to Wiki download page ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

Author: aparcar

README.md

@@ -11,6 +11,24 @@ full customization, to use the device in ways never envisioned.
 
 Sunshine!
 
+## Download
+
+Built firmware images are available for many architectures and come with a
+package selection to be used as WiFi home router. To quickly find a factory
+image usable to migrate from a vendor stock firmware to OpenWrt, try the
+*Firmware Selector*.
+
+* [OpenWrt Firmware Selector](https://firmware-selector.openwrt.org/)
+
+If your device is supported, please follow the **Info** link to see install
+instructions or consult the support resources listed below.
+
+## 
+
+An advanced user may require additional or specific package. (Toolchain, SDK, ...) For everything else than simple firmware download, try the wiki download page:
+
+* [OpenWrt Wiki Download](https://openwrt.org/downloads)
+
 ## Development
 
 To build your own firmware you need a GNU/Linux, BSD or MacOSX system (case