Remove CODE_OF_CONDUCT.md and use the organization-wide CODE OF CONDUCT file (#3285)

Author: seisman

CODE_OF_CONDUCT.md

@@ -9,7 +9,6 @@ exclude .gitignore
 exclude .pre-commit-config.yaml
 exclude .readthedocs.yaml
 exclude AUTHORSHIP.md
-exclude CODE_OF_CONDUCT.md
 exclude CONTRIBUTING.md
 exclude Makefile
 exclude environment.yml

MANIFEST.in

@@ -16,7 +16,7 @@
 [![Digital Object Identifier for the Zenodo archive](https://zenodo.org/badge/DOI/10.5281/3781524.svg)](https://doi.org/10.5281/zenodo.3781524)
 [![PyOpenSci](https://tinyurl.com/y22nb8up)](https://github.com/pyOpenSci/software-review/issues/43)
 [![GitHub license](https://img.shields.io/github/license/GenericMappingTools/pygmt?style=flat-square)](https://github.com/GenericMappingTools/pygmt/blob/main/LICENSE.txt)
-[![Contributor Code of Conduct](https://img.shields.io/badge/Contributor%20Covenant-v2.1%20adopted-ff69b4.svg)](CODE_OF_CONDUCT.md)
+[![Contributor Code of Conduct](https://img.shields.io/badge/Contributor%20Covenant-v2.1%20adopted-ff69b4.svg)](https://github.com/GenericMappingTools/.github/blob/main/CODE_OF_CONDUCT.md)
 
 <!-- doc-index-start-after -->