Add basic documentation for transactions

docs/Home.md

@@ -20,5 +20,6 @@ The following pages will tell you how to use it:
 * [Remove](Remove.md)
 * [Functions](Functions.md)
 * [Prepared Statements](Prepared-Statements.md)
+* [Transactions](Transactions.md)
 * [NULL](NULL.md)
 * [New Features](New-Features.md)

docs/Transactions.md

@@ -0,0 +1,44 @@
+# Transactions
+
+Transactions are simple in sqlpp11. Assuming you have a connection called `db`,
+you can start and commit a transaction just like this:
+
+```C++
+auto tx = start_transaction(db);
+// do something
+tx.commit();
+```
+
+If you need to rollback the transaction, you can call it's `rollback()` member,
+for instance like this:
+
+```C++
+auto tx = start_transaction(db);
+try
+{
+  // do something
+  tx.commit();
+}
+catch (...)
+{
+  tx.rollback();
+}
+```
+
+In case you call neither `commit()` nor `rollback()` on a transaction before it
+goes out of scope, it will call `rollback()` in its destructor. This automatic
+rollback will be reported by the connection.
+
+## More options
+You can turn off reporting for automatic rollback in the destructor by passing
+`sqlpp::quiet_auto_rollback`.
+
+```C++
+auto tx = start_transaction(db, sqlpp::quiet_auto_rollback);
+```
+
+You can also specify the isolation level for the transaction:
+
+```C++
+auto tx = start_transaction(db, ::sqlpp::isolation_level::repeatable_read);
+```