gh-119786: Move garbage collection doc from devguide to InternalDocs (#125282)

Co-Authored-By: Carol Willing carolcode@willingconsulting.com
Co-Authored-By: Ezio Melotti ezio.melotti@gmail.com
Co-Authored-By: Hugo van Kemenade hugovk@users.noreply.github.com
Co-Authored-By: Itamar Ostricher itamarost@gmail.com
Co-Authored-By: Jesús Cea jcea@jcea.es
Co-Authored-By: Joannah Nanjekye 3317755+nanjekyejoannah@users.noreply.github.com
Co-Authored-By: Ned Batchelder ned@nedbatchelder.com
Co-Authored-By: Pablo Galindo Salgado Pablogsal@gmail.com
Co-Authored-By: Pamela Fox pamela.fox@gmail.com
Co-Authored-By: Sam Gross colesbury@gmail.com
Co-Authored-By: Stefan Pochmann 609905+pochmann@users.noreply.github.com
Co-Authored-By: T. Wouters thomas@python.org
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Co-Authored-By: slateny 46876382+slateny@users.noreply.github.com
Co-Authored-By: Борис Верховский boris.verk@gmail.com
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Jacob Coffee <jacob@z7x.org>

Author: 3 people

InternalDocs/README.md

@@ -22,4 +22,6 @@ it is not, please report that through the
 
 [The Source Code Locations Table](locations.md)
 
+[Garbage collector design](garbage_collector.md)
+
 [Exception Handling](exception_handling.md)