chore: added entry for CHANGES.md

Signed-off-by: Sachin Beniwal <s474996633@gmail.com>

Author: benodiwal

doc/changes/fixed/12844.md

@@ -0,0 +1,7 @@
+- Improve error messages for invalid version formats containing non-ASCII
+  characters. Previously, non-ASCII characters in version strings (e.g., `(lang
+  dune è)` or `(using menhir π3.14)`) would fail with a generic "Invalid file"
+  error. Now they display a clear message: "Invalid atom: contains non-ASCII
+  character(s). Atoms must only contain ASCII characters." The fix is
+  implemented at the lexer level, providing consistent error handling across all
+  s-expression parsing. (#12844, fixes #12836, @benodiwal)