introduce docs -> models section mostly finished

docs_src/models/docs005.py

@@ -0,0 +1,51 @@
+import databases
+import sqlalchemy
+
+import orm
+
+database = databases.Database("sqlite:///db.sqlite")
+metadata = sqlalchemy.MetaData()
+
+
+class Course(orm.Model):
+    __database__ = database
+    __metadata__ = metadata
+
+    id = orm.Integer(primary_key=True)
+    name = orm.String(length=100)
+    completed = orm.Boolean(default=False)
+
+print(Course.__model_fields__)
+"""
+Will produce:
+{
+'id':   {'name': 'id', 
+         'primary_key': True, 
+         'autoincrement': True, 
+         'nullable': False, 
+         'default': None, 
+         'server_default': None, 
+         'index': None, 
+         'unique': None, 
+         'pydantic_only': False}, 
+'name':  {'name': 'name', 
+          'primary_key': False, 
+          'autoincrement': False, 
+          'nullable': True, 
+          'default': None, 
+          'server_default': None, 
+          'index': None, 
+          'unique': None, 
+          'pydantic_only': False, 
+          'length': 100}, 
+'completed': {'name': 'completed', 
+              'primary_key': False, 
+              'autoincrement': False, 
+              'nullable': True, 
+              'default': False, 
+              'server_default': None, 
+              'index': None, 
+              'unique': None, 
+              'pydantic_only': False}
+}
+"""