Add Paul to coredevs on about.md (#419)

* Add Paul to coredevs on about.md

* Adding Brady as well

Welcome, @p-j-smith and @BradyAJohnston!

Author: jennaswa

about.md

@@ -89,13 +89,15 @@ The current
 [@MDAnalysis/coredevs](https://github.com/orgs/MDAnalysis/teams/coredevs/members)
 team ("MDAnalysis Core Developers") consists of:
 
+- @BradyAJohnston
 - @fiona-naughton
 - @hmacdope
 - @IAlibay
 - @jennaswa
 - @lilyminium
 - @micaela-matta
 - @orbeckst
+- @p-j-smith
 - @richardjgowers
 - @RMeli
 - @tylerjereddy