Add [Historical note] to changelog.d

Author: zlonast

changelog.d/pr-10969.md

@@ -13,6 +13,13 @@ similarly as `ghc-options` should be always used when
 invoking `ghc` - regardless of what is the intention of a particular GHC-call.
 GHC might use or not use the options, Cabal cannot know and should not guess.
 
+[Historical note]
+Before `ghc` 8.10, `cc-options` and `cxx-options` were split into one flag `-optc`,
+then in 8.10 they started to split into `-optc` and `-optcxx`, cabal picked up
+this change and started to give flags separately not only for new versions,
+but also for old ones. That is, now for 8.8 we send `-optc` flags separately for
+different sources.
+
 `cc-options` and `cxx-options` still need to be separated (C/C++) for versions below 8.10.
 
 gccProgram till need to be separated (C/C++) for versions below 9.4.