add experts index entries for deepfreeze, frozen modules and subinterpreters (#1033)

* add Kumar Aditya to experts list

* sort it

* add Guido and Eric

* Update core-developers/experts.rst

Author: kumaraditya303

core-developers/experts.rst

@@ -285,6 +285,7 @@ Tools
 Tool                Maintainers
 ==================  ===========
 Argument Clinic     larryhastings
+Deepfreeze          gvanrossum, kumaraditya303
 PEG Generator       gvanrossum, pablogsal, lysnikolaou
 ==================  ===========
 
@@ -334,6 +335,7 @@ documentation       ezio-melotti, merwok, JulienPalard, willingc, hugovk
 emoji               Mariatta
 extension modules   encukou, ncoghlan
 filesystem          giampaolo
+frozen modules      ericsnowcurrently, gvanrossum, kumaraditya303
 f-strings           ericvsmith*
 GUI
 i18n                malemburg, merwok
@@ -355,6 +357,7 @@ release management  tarekziade, malemburg, benjaminp, warsaw,
                     gvanrossum, anthonybaxter^, merwok, ned-deily,
                     birkenfeld, JulienPalard
 str.format          ericvsmith*
+subinterpreters     ericsnowcurrently, kumaraditya303
 testing             voidspace, ezio-melotti
 test coverage
 threads             gpshead