Fix Changelog notation

Remove backticks, since ChangeLog is not in MarkDown
diff --git a/ChangeLog b/ChangeLog
index f8dcae5..4eb52fb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,8 +3,8 @@
 = mbed TLS x.x.x branch released xxxx-xx-xx
 
 Bugfix
-   * Fix compilation error on Mingw32 when `_TRUNCATE` is defined. Use `_TRUNCATE`
-     only if `__MINGW32__` not defined. Fix suggested by Thomas Glanzmann and
+   * Fix compilation error on Mingw32 when _TRUNCATE is defined. Use _TRUNCATE
+     only if __MINGW32__ not defined. Fix suggested by Thomas Glanzmann and
      Nick Wilson on issue #355
 
 = mbed TLS 2.6.0 branch released 2017-08-10