AUTHORS.md: add additional copyright holders

Add additional copyright holders found by grepping for copyright
statements in the source code. Some of these are copyright holders that
are not explicitly mentioned in the logs (Intel, MaxLinear), others are
from code that we copied from somewhere else.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

AUTHORS.md

@@ -18,12 +18,14 @@ This file lists all contributors.
 - Fancy Qian
 - Frederik Van Bogaert
 - Gal Wiener
+- Intel Corporation
 - Itay Elenzweig
 - Juan Schroeder
 - KC Chen
 - Lior Amram
 - Maksym Bielan
 - Mario Maz
+- MaxLinear
 - Moran Shoeg
 - Ostap Slyusar
 - Pavel Levitsky
@@ -38,3 +40,14 @@ This file lists all contributors.
 - Yevheniy-Vilhelm Vall
 - Yaniv Yitzhak
 - Yuriy Masechko
+
+In addition, some parts were copied from other projects.
+
+- nl80211_client_impl.cpp contains code copied from [`iw`](http://git.sipsolutions.net/iw.git/)
+  - Johannes Berg
+  - Andy Lutomirski
+  - Mike Kershaw
+  - Luis R. Rodriguez
+- easylogging++ is forked from https://github.com/amrayn/easyloggingpp
+  - Zuhd Web Services
+  - @abumusamq