Add FUNDING.json

We have been contacted by Monet du Plessis of the etherium foundation and
Natascha Buck (Grants at the Better Internet Foundation)

"The Ethereum Foundation is thrilled to inform you that your contribution to
 open-source software development through your work on ffmpeg
 https://github.com/FFmpeg/FFmpeg  has been recognized and rewarded by the
 Devcon team! Your project played a fundamental role in the success of Devcon
 <http://devcon.org/>, helping to create a more meaningful experience for
 the Ethereum community. In collaboration with Drips Network
 <https://www.drips.network/>, we are pleased to award you $2,240.00 in
 appreciation of your efforts and to support your continued efforts in
 open-source development."

To be able to claim donations through the drips network we need to
specify a wallet to do so in FUNDING.json

This will also allow FFmpeg to receive future funding and donations
through the drips network.

The specified wallet is a safe wallet backed by a ledger hw wallet.
We can later change who controls the safe wallet. (For example it
could be passed on to the SPI treasurer)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

FUNDING.json

@@ -0,0 +1,7 @@
+{
+  "drips": {
+    "ethereum": {
+      "ownedBy": "0x2f3900e7064eE63D30d749971265858612AA7139"
+    }
+  }
+}