[committers-guide] Remove obsolete miscellaneous question

[fernape]

Summary

The src tree already uses git. Remove subversion reference.

Test Plan

• Renders OK.

[0mp]

Actually, I'd get rid of this section completely. Adding a file in Subversion was indeed tricky, but in the Git world it is just a part of the workflow. I cannot imagine this section being helpful to any committer in the future.

[fernape]

• [committers-guide] Remove obsolete misc question

[0mp]

I'd add a note to the commit message that adding files in the Git world is pretty straightforward and does not require any special considerations in contrast to Subversion and that's why this section is obsolete.