Use correct DOT language syntax for an ID with a leading digit (0mp).

[0mp]

Summary

It turns out that my username (0mp) is not a valid ID in the DOT language
because it starts with a digit. The easiest way to fix it is to put my username
in double quotes [1].

[1]: https://graphviz.gitlab.io/_pages/doc/info/lang.html

Reported by: pstef

Test Plan

Running dot share/misc/committers-ports.dot should not produce the following messages:

Warning: syntax ambiguity - badly delimited number '0m' in line 43 of share/misc/committers-ports.dot splits into two tokens
Warning: syntax ambiguity - badly delimited number '0m' in line 484 of share/misc/committers-ports.dot splits into two tokens
Warning: syntax ambiguity - badly delimited number '0m' in line 530 of share/misc/committers-ports.dot splits into two tokens