add nsf acks to four proposals

proposals/300-walking-onions.txt

@@ -499,6 +499,8 @@ A.1. Acknowledgments
    Thanks to David Goulet, Teor, and George Kadianakis for commentary on
    earlier versions of this draft.
 
+   This research was supported by NSF grants CNS-1526306 and CNS-1619454.
+
 A.2. Additional ideas
 
    Teor notes that there are ways to try to get this idea to apply to

proposals/302-padding-machines-for-onion-clients.txt

@@ -291,6 +291,10 @@ NOTE: Please look at section 3 of padding-spec.txt now, not this document.
    circuits, and also what other classifiers can be built using deep learning
    and whatnot.
 
+A. Acknowledgements
+
+   This research was supported by NSF grants CNS-1526306 and CNS-1619454.
+
 ---
 
    [0]: https://www.usenix.org/node/190967

proposals/305-establish-intro-dos-defense-extention.txt

@@ -191,6 +191,10 @@ Status: Closed
    or very popular which could mean time to increase or disable the denial of
    service defenses.
 
+A. Acknowledgements
+
+   This research was supported by NSF grants CNS-1526306 and CNS-1619454.
+
 References:
 
 [1] https://lists.torproject.org/pipermail/tor-dev/2019-May/013837.html

proposals/307-onionbalance-v3.txt

@@ -178,3 +178,5 @@ A. Acknowledgments
    Thanks to the network team for helping me clarify my ideas here, explore
    options, and better understand some of the implementations and challenges
    in this problem space.
+
+   This research was supported by NSF grants CNS-1526306 and CNS-1619454.