mysql://user:pass@host/dbname instead of pass:host

Summary:
Reading [1 sqlalchemy.future.Engine](https://docs.sqlalchemy.org/en/14/core/future.html#sqlalchemy.future.Engine) and [2 sqlalchemy.create_engine](https://docs.sqlalchemy.org/en/14/core/engines.html#sqlalchemy.create_engine). I fond @ should be used between pass & host. 

Test Plan:
I checked with sqlalchemy 1.4.22 locally and I think @ should be used.

doc/build/glossary.rst

@@ -37,7 +37,7 @@ Glossary
             from sqlalchemy.orm import sessionmaker
 
 
-            engine = create_engine("mysql://user:pass:host/dbname", future=True)
+            engine = create_engine("mysql://user:pass@host/dbname", future=True)
             Session = sessionmaker(bind=engine, future=True)
 
         **ORM Queries in 2.0 style**