Add documentation and rename main file

.gitignore

@@ -109,3 +109,6 @@ venv.bak/
 .mypy_cache/
 .dmypy.json
 dmypy.json
+
+# database files (may contain sensitive student info)
+*.db

README.md

@@ -1,11 +1,62 @@
 # ib-clearance
 
-_Insert description here_
+ib-clearance is a program which helps schools manage the entrance and exiting of their IB students. Due to the unique nature of IB students' timetables, the program helps check individual timetables and give clearance to students who have finished for the day.
 
 ### Building
 
+The code is currently designed to run on Python 3.6.*.
+
+I recommend building executables with `pyinstaller` with `pyinstaller --onefile ib-clearance.py`.
+
 ### Lesson IDs
 
+Equivalents of lesson names for use in class databases.
+
+- Academic Writing
+    - 'aw'
+- Biology
+    - 'bi'
+- Business Management
+    - 'bm'
+- Chemistry
+    - 'ch'
+- Computer Science
+    - 'cs'
+- Economics
+    - 'ec'
+- English A
+    - 'ena'
+- English B
+    - 'enb'
+- French
+    - 'fr'
+- Geography
+    - 'ge'
+- German
+    - 'de'
+- Guidance
+    - 'gu'
+- Mathematical Studies
+    - 'mst'
+- Mathematics HL
+    - 'mhl'
+- Mathematics SL
+    - 'msl'
+- Polish A
+    - 'pl'
+- Psychology
+    - 'ps'
+- Self-Taught Language A
+    - 'st'
+- Spanish
+    - 'es'
+- Theory of Knowledge
+    - 'tok'
+- Turkish A
+    - 'tr'
+- Visual Arts
+    - 'va'
+
 ## License
 
 Copyright (C) 2018  Abdulkadir Furkan Şanlı