Update thread safety status of the driver to reflect reality; that be…

…ing that the driver is not thread safe (#928)

docs/documentation/head/thread.md

@@ -9,30 +9,12 @@ nexttitle: Chapter 11. Connection Pools and Data Sources
 next: datasource.html
 ---
 
-A problem with many JDBC drivers is that only one thread can use a `Connection`
-at any one time --- otherwise a thread could send a query while another one is
-receiving results, and this could cause severe confusion.
 
-The PostgreSQL™ JDBC driver is thread safe. Consequently, if your application
-uses multiple threads then you do not have to worry about complex algorithms to
-ensure that only one thread uses the database at a time.
+The PostgreSQL™ JDBC driver is not thread safe. 
+The PostgreSQL server is not threaded. Each connection creates a new process on the server; 
+as such any concurrent requests to the process would have to be serialized. 
+The driver makes no guarantees that methods on connections are synchronized. 
+It will be up to the caller to synchronize calls to the driver.
 
-If a thread attempts to use the connection while another one is using it, it
-will wait until the other thread has finished its current operation.  If the
-operation is a regular SQL statement, then the operation consists of sending the
-statement and retrieving any `ResultSet` (in full). If it is a fast-path call
-(e.g., reading a block from a large object) then it consists of sending and
-retrieving the respective data.
-
-This is fine for applications and applets but can cause a performance problem
-with servlets. If you have several threads performing queries then each but one
-will pause. To solve this, you are advised to create a pool of connections. When
-ever a thread needs to use the database, it asks a manager class for a `Connection`
-object. The manager hands a free connection to the thread and marks it as busy.
-If a free connection is not available, it opens one.  Once the thread has
-finished using the connection, it returns it to the manager which can then either
-close it or add it to the pool. The manager would also check that the connection
-is still alive and remove it from the pool if it is dead.  The down side of a
-connection pool is that it increases the load on the server because a new session
-is created for each `Connection` object.  It is up to you and your applications's
-requirements.
+A noteable exception is org/postgresql/jdbc/TimestampUtils.java which is threadsafe.
+