feat: Add Maintainer policy

docs/MaintainerTeam.md

@@ -0,0 +1,26 @@
+# The Maintainer Team
+
+The default policies around the maintainer team are those of Mathlib, and where conflict
+or disagreement arises these are the fall-back.
+
+## Role
+
+The role of the maintainer team is to:
+
+1. Give final reviews of pull-requests.
+2. Help structure and guide the project.
+3. Help foster a pleasant and active community around the project.
+
+## Becoming a maintainer
+
+Maintainers have research-level knowledge of physics or mathematics, and have
+experience with either the PhysLean or Mathlib review process.
+
+To become a maintainer, you either need an invitation from current maintainers, or
+need to nominate yourself to a current maintainer.
+
+## Term of a maintainer
+
+A maintainer will serve for a period for one-year, which will renew unless they are
+inactive for a period of 6 months before renewal or wish to step down (which they can
+do at any point).