Trim LaTeX comment, obsolete as of latest TeXLive fontawesome6 and 7 (#13909)

Author: jfbu

sphinx/texinputs/sphinx.sty

@@ -931,10 +931,6 @@
 % Icon defaults depending on package used.
 % Attention! no extra spaces (to align here) when using \@namedef!
 
-% MEMO: the [regular] style mark-up for {lightbulb} was inherited
-% from fontawesome5 and found experimentally to work also with
-% fontawesome6 (and fontawesome7) despite their respective PDF docs
-% not mentioning it...
 \@namedef{spx@fontawesome6@note}{\faIcon{circle-info}}
 \@namedef{spx@fontawesome6@hint}{\faIcon[regular]{lightbulb}}
 \@namedef{spx@fontawesome6@tip}{\faIcon[regular]{lightbulb}}