Remove the list of core developers (#3927)

We now have a new governance model with a link to AMReX Contributors.

CONTRIBUTING.md

@@ -271,41 +271,3 @@ to be documented where appropriate. For example:
 ```
 Additional information regarding Doxygen comment formatting can be found
 in the [Doxygen Manual](https://www.doxygen.nl/manual/).
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-
-
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-## Core Developers
-
-People who make a number of substantive contributions will be named
-"core developers" of AMReX.  The criteria for becoming a core
-developer are flexible, but generally involve one of the following:
-
-  * 100 non-trivial commits to `amrex/Src/`  *and/or*
-
-  * addition of a new algorithm / module  *and/or*
-
-  * substantial input into the code design process or testing
-
-If a core developer is inactive for multiple years, we may reassess their
-status as a core developer.
-
-The current list of core developers is:
-Ann Almgren (LBNL),
-Vince Beckner,
-John Bell (LBNL),
-Johannes Blaschke (LBNL),
-Cy Chan (LBNL),
-Marcus Day (LBNL),
-Brian Friesen (NERSC),
-Kevin Gott (NERSC),
-Daniel Graves (LBNL),
-Axel Huebl (LBNL),
-Max Katz (NVIDIA),
-Andrew Myers (LBNL),
-Tan Nguyen (LBNL),
-Andrew Nonaka (LBNL),
-Michele Rosso (LBNL),
-Sam Williams (LBNL),
-Weiqun Zhang (LBNL),
-Michael Zingale (Stony Brook University).