רַבִּי שִׁמְעוֹן אוֹמֵר, שְׁלשָׁה כְתָרִים הֵם,
כֶּתֶר תּוֹרָה וְכֶתֶר כְּהֻנָּה וְכֶתֶר מַלְכוּת,
:וְכֶתֶר שֵׁם טוֹב עוֹלֶה עַל גַּבֵּיהֶן
Rabbi Shimon said: There are three crowns:
the crown of Torah, the crown of priesthood, and the crown of royalty, but the crown of a good name supersedes them all. (Avos 4,13)
The commentators (see Bartenura or Mahzor Vitri) explain the importance of achieving the "crown of a good name" by good deeds and respectful conducts, however, I couldn't spot it anywhere in the later Halachah (Rambam or Shu"A, etc).
Is it so and if yes, why the most important "crown of a good name" (כתר שם טוב) didn't make its way to the Jewish Halachah?