Update docs/source/carrierboard_development.rst

Co-authored-by: barsnick <barsnick@users.noreply.github.com>

Author: mhei

docs/source/carrierboard_development.rst

@@ -163,7 +163,7 @@ files in the root filesystem of the firmware in the ``/boot`` directory.
 Loading of such files can be controlled with the U-Boot environment variable ``overlays``. This variable can hold a whitespace
 separated list of filenames (basename of the file, i.e. without ``/boot`` prefix) which are loaded and merged
 in order *after* the base Device Tree file (given via ``fdtfile`` environment variable) is loaded.
-This approach can also be used for custom carrier board when the EEPROM approach does not fit.
+This approach can also be used for a custom carrier board when the EEPROM approach does not fit.
 
 Here is a summary of related U-Boot environment variables: