use dashes instead of plus signs (for Sphinx compatibility)

AUTHORS.md

@@ -2,18 +2,18 @@
 
 The current maintainers of Adaptive are:
 
-+ [Bas Nijholt](<http://nijho.lt>)
-+ [Joseph Weston](<https://joseph.weston.cloud>)
-+ [Anton Akhmerov](<https://antonakhmerov.org>)
+- [Bas Nijholt](<http://nijho.lt>)
+- [Joseph Weston](<https://joseph.weston.cloud>)
+- [Anton Akhmerov](<https://antonakhmerov.org>)
 
 Other contributors to Adaptive include:
 
-+ Andrey E. Antipov
-+ [Christoph Groth](<http://inac.cea.fr/Pisp/christoph.groth/>)
-+ Jorn Hoofwijk
-+ Philippe Solodov (@philippeitis)
-+ Victor Negîrneac (@caenrigen)
-+ Thomas A Caswell (@tacaswell)
-+ Álvaro Gómez Iñesta (@AlvaroGI)
-+ Sultan Orazbayev (@SultanOrazbayev)
-+ Thomas Aarholt (@thomasaarholt)
+- Andrey E. Antipov
+- [Christoph Groth](<http://inac.cea.fr/Pisp/christoph.groth/>)
+- Jorn Hoofwijk
+- Philippe Solodov (@philippeitis)
+- Victor Negîrneac (@caenrigen)
+- Thomas A Caswell (@tacaswell)
+- Álvaro Gómez Iñesta (@AlvaroGI)
+- Sultan Orazbayev (@SultanOrazbayev)
+- Thomas Aarholt (@thomasaarholt)