docs: remove unrelated draft link to open-mesh.org in README

This was an idea (thought experiment?) from a Wireless Battlemesh ages
ago between batman-adv devs. Regarding what could be done to interconnect
isolated/separate WiFi mesh clouds on layer 3 without losing best path
metric information, without worsening/compromising on the best route decision.
And as a more sophisticated approach to the batman-adv gateway feature and
a potential replacement for tunneled batman-adv over VPN connections.

Which is the opposite of what the sentence in this Gluon README
is saying. And this never got implemented in either batman-adv nor Gluon.

Therefore removing this link to this old draft page.

README.md

@@ -10,7 +10,7 @@ Gluon is a firmware framework to build preconfigured OpenWrt images for public m
 
 Gluon provides an easy-to-use firmware for a public, decentral WLAN and/or wire based mesh network.
 Common network capable devices, like smartphones, laptops or desktop PCs can connect to the mesh network and communicate over it, without the need of passwords for access and without the need of installing special software.
-Additionally, internet access and [merging mesh clouds](https://www.open-mesh.org/projects/batman-adv/wiki/Connecting-Batman-adv-clouds) can be accomplished over a WAN through VPN connected gateways.
+Additionally, internet access and merging mesh clouds can be accomplished over a WAN through VPN connected gateways.
 
 Gluon's features include: