[openwrt/openwrt] README: add download section

[LEDE Commits]

ansuel pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/13cae3cdce34a600cfbdd7eac82d8fb50cda3f1d

commit 13cae3cdce34a600cfbdd7eac82d8fb50cda3f1d
Author: Paul Spooren <mail at aparcar.org>
AuthorDate: Wed Sep 8 22:57:46 2021 -1000

    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 at aparcar.org>
    [ fix typo in commit description, add link to Wiki download page ]
    Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 README.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/README.md b/README.md
index 2eff292321..29ff89f90c 100644
--- a/README.md
+++ b/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