README: rename "architectural overview" section and move close to top

README.md

@@ -14,6 +14,15 @@ Copyright (c) 2020 Joakim Frostegård
 
 Distributed under Apache 2.0 license (details in `LICENSE` file.)
 
+## Technical overview
+
+One or more socket workers open sockets, read and parse requests from peers and
+send them through channels to request workers. They in turn go through the
+requests, update internal state as appropriate and generate responses, which
+are sent back to the socket workers, which serialize them and send them to
+peers. This design means little waiting for locks on internal state occurs,
+while network work can be efficiently distributed over multiple threads.
+
 ## Installation prerequisites
 
 - Install Rust with [rustup](https://rustup.rs/) (stable is recommended)
@@ -203,15 +212,6 @@ Enter a password when prompted. Then move `identity.pfx` somewhere suitable,
 and enter the path into the tracker configuration field `tls_pkcs12_path`. Set
 the password in the field `tls_pkcs12_password` and set `use_tls` to true.
 
-## Architectural overview
-
-One or more socket workers open sockets, read and parse requests from peers and
-send them through channels to request workers. They in turn go through the
-requests, update internal state as appropriate and generate responses, which
-are sent back to the socket workers, which serialize them and send them to
-peers. This design means less waiting for locks on internal state has to occur,
-while network work can be efficiently distributed over multiple threads.
-
 ## Trivia
 
 The tracker is called aquatic because it thrives under a torrent of bits ;-)