Typo Update blip-0003.md

"sponaneous" correct spelling: "spontaneous"

Corrected.

Author: mdqst

blip-0003.md

@@ -45,7 +45,7 @@ Receiver:
 
 A convenience of layer 1 bitcoin is being able to spontaneously send to a
 bitcoin address with no advance work required on the part of the payee. Keysend
-brings the convenience of sponaneous payments to layer 2 (with a few caveats,
+brings the convenience of spontaneous payments to layer 2 (with a few caveats,
 see the [Drawbacks](#keysend-drawbacks) section).
 
 As previously mentioned, keysend also has the advantage of already being