Fix typo

CONFIG.md

@@ -108,7 +108,7 @@ Defining `HB_NO_FALLBACK_SHAPE` however is pretty harmless.  That removes the
 By default HarfBuzz builds as a thread-safe library.  The exception is that
 the `HB_TINY` predefined configuring (more below) disables thread-safety.
 
-If you do /not/ need thread-safety in the library (eg. you always call into
+If you do *not* need thread-safety in the library (eg. you always call into
 HarfBuzz from the same thread), you can disable thread-safety by defining
 `HB_NO_MT`.  As noted already, this is enabled by `HB_TINY`.
 
@@ -144,7 +144,7 @@ overrides at the end.
 ## Notes
 
 Note that the config option `HB_NO_CFF`, which is enabled by `HB_LEAN` and
-`HB_TINY` does /not/ mean that the resulting library won't work with CFF fonts.
+`HB_TINY` does *not* mean that the resulting library won't work with CFF fonts.
 The library can shape valid CFF fonts just fine, with or without this option.
-This option disables (among other things) the code to calculate glyph exntents
+This option disables (among other things) the code to calculate glyph extents
 for CFF fonts.