pkstrings: Add some module level doc

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

pkstrings/src/pkstring.rs

@@ -13,6 +13,13 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
+//! Handles string encoding and decoding for the English version of Pokémon Gen 1.
+//!
+//! Documentation can be found at:
+//! https://bulbapedia.bulbagarden.net/wiki/Character_encoding_(Generation_I)
+//!
+//! Control characters are considered valid but not handled yet.
+
 use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;