AntennaPod: use localizable texts to allow upstream's translations

upstream uses fastlane:
https://fdroid.gitlab.io/fdroid-website/docs/All_About_Descriptions_Graphics_and_Screenshots

metadata/de.danoeh.antennapod.txt

@@ -7,28 +7,6 @@ Changelog:https://raw.githubusercontent.com/AntennaPod/AntennaPod/1.6.0_devel/CH
 Bitcoin:1DzvtuvdW8VhDsq9GUytMyALmsHeaHEKbg
 
 Auto Name:AntennaPod
-Summary:Advanced podcast manager and player
-Description:
-Podcast manager and player that gives you instant access to millions of free and
-paid podcasts, from independent podcasters to large publishing houses such as
-the BBC, NPR and CNN. Add, import and export their feeds hassle-free using the
-iTunes podcast database, gPodder, OPML files or simple RSS URLs. Save effort,
-battery power and mobile data usage with powerful automation controls for
-downloading episodes (specify times, intervals and WiFi networks) and deleting
-episodes (based your favourites and delay settings). But most importantly:
-Download, stream or queue episodes and enjoy them the way you like with
-adjustable playback speeds, chapter support and a sleep timer.
-
-Made by podcast-enthousiasts, AntennaPod is kept free of ads and frequently
-updated based on your input.
-
-'''N.B.''' The Flattr functionality is disabled in this build as the API keys
-are not in the source.
-
-Check out the
-[https://github.com/AntennaPod/AntennaPod/wiki/About-AntennaPod#all-features
-full feature list] over at our Wiki.
-.
 
 Repo Type:git
 Repo:https://github.com/danieloeh/AntennaPod.git
@@ -390,6 +368,11 @@ Build:1.6.2.3,1060203
     gradle=free
     gradleprops=freeBuild
 
+Maintainer Notes:
+Summary and Description have been moved to the new localizable text files:
+https://f-droid.org/docs/All_About_Descriptions_Graphics_and_Screenshots
+.
+
 Auto Update Mode:Version %v
 Update Check Mode:Tags
 Current Version:1.6.2.3

metadata/de.danoeh.antennapod/en-US/description.txt

+Podcast manager and player that gives you instant access to millions of free and
+paid podcasts, from independent podcasters to large publishing houses such as
+the BBC, NPR and CNN. Add, import and export their feeds hassle-free using the
+iTunes podcast database, gPodder, OPML files or simple RSS URLs. Save effort,
+battery power and mobile data usage with powerful automation controls for
+downloading episodes (specify times, intervals and WiFi networks) and deleting
+episodes (based your favourites and delay settings). But most importantly:
+Download, stream or queue episodes and enjoy them the way you like with
+adjustable playback speeds, chapter support and a sleep timer.
+
+Made by podcast-enthousiasts, AntennaPod is kept free of ads and frequently
+updated based on your input.
+
+'''N.B.''' The Flattr functionality is disabled in this build as the API keys
+are not in the source.
+
+Check out the
+[https://github.com/AntennaPod/AntennaPod/wiki/About-AntennaPod#all-features
+full feature list] over at our Wiki.

metadata/de.danoeh.antennapod/en-US/summary.txt

+Advanced podcast manager and player