Update documentation for QT removal.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

contrib/README.md

@@ -1,3 +1,5 @@
+*** Warning: This document has not been updated for Zcash and may be inaccurate. ***
+
 Wallet Tools
 ---------------------
 

doc/developer-notes.md

@@ -105,9 +105,6 @@ error and debugging messages are written there.
 The -debug=... command-line option controls debugging; running with just -debug or -debug=1 will turn
 on all categories (and give you a very large debug.log file).
 
-The Qt code routes qDebug() output to debug.log under category "qt": run with -debug=qt
-to see it.
-
 **testnet and regtest modes**
 
 Run with the -testnet option to run with "play zcash" on the test network, if you

doc/translation_strings_policy.md

@@ -10,8 +10,6 @@ How to translate?
 
 To mark a message as translatable
 
-- In GUI source code (under `src/qt`): use `tr("...")`
-
 - In non-GUI source code (under `src`): use `_("...")`
 
 No internationalization is used for e.g. developer scripts outside `src`.