[NFC] Inclusive Language: change master to main for .chm files

[NFC] As part of using inclusive language within the llvm project,
this patch replaces master with main when referring to `.chm` files.

Reviewed By: teemperor

Differential Revision: https://reviews.llvm.org/D113299

GitOrigin-RevId: c3b15b71ce009b3dff9fb3bd664d087057b8376e
diff --git a/docs/doxygen.cfg.in b/docs/doxygen.cfg.in
index 36786aa..c2f9f7f 100644
--- a/docs/doxygen.cfg.in
+++ b/docs/doxygen.cfg.in
@@ -1220,7 +1220,7 @@
 HHC_LOCATION           =
 
 # The GENERATE_CHI flag controls if a separate .chi index file is generated (
-# YES) or that it should be included in the master .chm file ( NO).
+# YES) or that it should be included in the main .chm file ( NO).
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTMLHELP is set to YES.