Add CC0 copyright notice on specs (#38)

mdf.md

@@ -16,6 +16,7 @@
 5. [Footnotes](#footnotes)
 6. [Changelog](#changelog)
 7. [Acknowledgements](#acknowledgements)
+8. [Copyright](#copyright)
 
 ## Abstract
 
@@ -91,3 +92,7 @@ Nodes SHOULD send ephemeral messages in batch mode. As their delivery is not nee
 
 ## Acknowledgements
  - Andrea Maria Piana
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).

mvds.md

@@ -19,6 +19,7 @@
 6. [Footnotes](#footnotes)
 7. [Changelog](#changelog)
 8. [Acknowledgements](#acknowledgements)
+9. [Copyright](#copyright)
 
 ## Abstract
 
@@ -166,3 +167,7 @@ MVDS has been formally specified using TLA+: <https://github.com/vacp2p/formalit
  - Greg Markou
  - Rene Nayman
  - Jacek Sieka
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).

remote-log.md

@@ -20,6 +20,7 @@
 5. [Footnotes](#footnotes)
 6. [Changelog](#changelog)
 7. [Acknowledgements](#acknowledgements)
+8. [Copyright](#copyright)
 
 ## Abstract
 
@@ -237,3 +238,7 @@ in time.
 ## Acknowledgements
 
 TBD.
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).