qt: add transifex configuration file

This is a project-wide configuration file and should be the same for
everyone.
Also remove mention of creating it yourself from the translation process.

.tx/config

@@ -0,0 +1,7 @@
+[main]
+host = https://www.transifex.com
+
+[bitcoin.tx]
+file_filter = src/qt/locale/bitcoin_<lang>.ts
+source_file = src/qt/locale/bitcoin_en.ts
+source_lang = en

doc/translation_process.md

@@ -71,28 +71,8 @@ We are using https://transifex.com as a frontend for translating the client.
 https://www.transifex.com/projects/p/bitcoin/resource/tx/
 
 The "Transifex client" (see: http://support.transifex.com/customer/portal/topics/440187-transifex-client/articles)
-will help with fetching new translations from Transifex. Use the following
-config to be able to connect with the client:
-
-### .tx/config
-
-    [main]
-    host = https://www.transifex.com
-
-    [bitcoin.tx]
-    file_filter = src/qt/locale/bitcoin_<lang>.ts
-    source_file = src/qt/locale/bitcoin_en.ts
-    source_lang = en
-    
-### .tx/config (for Windows)
-
-    [main]
-    host = https://www.transifex.com
-
-    [bitcoin.tx]
-    file_filter = src\qt\locale\bitcoin_<lang>.ts
-    source_file = src\qt\locale\bitcoin_en.ts
-    source_lang = en
+will help with fetching new translations from Transifex. The Transifex configuration (`.tx/config`)
+is part of the repository.
 
 It is also possible to directly download new translations one by one from the Transifex website.