update documentation

Signed-off-by: Benjamin Brahmer <info@b-brahmer.de>

README.md

@@ -4,7 +4,7 @@
 
 [![Build Status](https://travis-ci.org/nextcloud/news.svg?branch=master)](https://travis-ci.org/nextcloud/news) [![Code coverage](https://img.shields.io/codecov/c/github/nextcloud/news.svg?style=flat-square)](https://codecov.io/gh/nextcloud/news/) [![irc](https://img.shields.io/badge/irc%20channel-%23nextcloud--news%20on%20freenode-blue.svg)](https://webchat.freenode.net/?channels=nextcloud-news)
 
-The News app is an RSS/Atom feed aggregator. It offers a [RESTful API](https://github.com/nextcloud/news/tree/master/docs/externalapi) for app developers. The source code is [available on GitHub](https://github.com/nextcloud/news)
+The News app is an RSS/Atom feed aggregator. It offers a [RESTful API](https://github.com/nextcloud/news/tree/master/docs/externalapi/Legacy.md) for app developers. The source code is [available on GitHub](https://github.com/nextcloud/news)
 
 ## Install and configuration
 See the [install document](https://github.com/nextcloud/news/blob/master/docs/install.md) and the [configuration overview](https://github.com/nextcloud/news/blob/master/docs/configuration.md)
@@ -32,7 +32,7 @@ Nextcloud News can be synced with the following apps:
   * [Nextcloud News Reader (Android)](https://play.google.com/store/apps/details?id=de.luhmer.owncloudnewsreader), [open source](https://github.com/nextcloud/news-android-app)
   * [OCReader (Android)](https://f-droid.org/repository/browse/?fdid=email.schaal.ocreader), [open source](https://github.com/schaal/ocreader)
   * [Newsout (Android)](https://play.google.com/store/apps/details?id=com.inspiredandroid.newsout), [open source](https://github.com/SimonSchubert/NewsOut)
-  * [Readrops (Android)](https://f-droid.org/en/packages/com.readrops.app/), [open source](https://github.com/readrops/Readrops)  
+  * [Readrops (Android)](https://f-droid.org/en/packages/com.readrops.app/), [open source](https://github.com/readrops/Readrops)
   * [CloudNews (iOS)](https://apps.apple.com/app/cloudnews-owncloud-news-reader/id683859706), [open source](https://github.com/owncloud/news-ios-app)
   * [Fiery Feeds (iOS)](https://apps.apple.com/us/app/fiery-feeds-rss-reader/id1158763303), closed source
   * [News Checker (Chrome extension)](https://chrome.google.com/webstore/detail/owncloud-news-checker/hnmagnmdnfdhabdlicankfbfhcdgbfhe)
@@ -44,7 +44,7 @@ Nextcloud News can be synced with the following apps:
   * [py3status](https://github.com/ultrabug/py3status/) for [i3 (UNIX-like)](http://i3wm.org/), [open source](https://github.com/i3/i3)
   * [newsboat](http://newsboat.org/) for Unix terminal, [open source](https://github.com/newsboat/newsboat)
   * [Newsie (Ubuntu Touch)](https://open-store.io/app/newsie.martinferretti), [open source](https://gitlab.com/ferrettim/newsie)
-  * [Liferea (Linux desktop)](https://lzone.de/liferea), [open source](https://github.com/lwindolf/liferea)  
+  * [Liferea (Linux desktop)](https://lzone.de/liferea), [open source](https://github.com/lwindolf/liferea)
 
 ## Custom Themes
 Nextcloud News can look different with the following themes:

appinfo/info.xml

@@ -31,11 +31,14 @@ Before you update to a new version, [check the changelog](https://github.com/nex
         <php min-version="7.2"/>
         <database min-version="10">pgsql</database>
         <database>sqlite</database>
-        <database min-version="5.5">mysql</database>
+        <database min-version="8.0">mysql</database>
         <lib min-version="2.7.8">libxml</lib>
         <lib>curl</lib>
+        <lib>dom</lib>
         <lib>SimpleXML</lib>
         <lib>iconv</lib>
+        <lib>json</lib>
+
         <owncloud max-version="0" min-version="0"/>
         <nextcloud min-version="20" max-version="21"/>
     </dependencies>

docs/install.md

@@ -1,27 +1,32 @@
 # Installation/Update
 
 ## Dependencies
-* PHP >= 7.0
-* Nextcloud 14
-* libxml >= 2.7.8 (2.9 recommended)
-* php-curl
+* PHP >= 7.2
+* Nextcloud 20
+* libxml >= 2.7.8
+You also need some PHP extensions:
+* json
+* simplexml
+* xml
+* dom
+* curl
 * iconv
-* SimpleXML
 
 ## Supported Databases
-* PostgreSQL >= 9.4 (recommended)
-* MariaDb >= 5.5
+* PostgreSQL >= 10
+* MariaDB >= 10.2
+* MySQL >= 8.0
 * SQLite (discouraged)
 
 ## Performance Notices
-* Use MySQL or PostgreSQL for better database performance
+* Use MySQL/MariaDB or PostgreSQL for better database performance
 * Use the [updater script to thread and speed up the update](https://github.com/nextcloud/news-updater)
 
 ## Before you install/update the News app
 Before you install the app do the following:
 * Check that your **nextcloud/data/** directory is owned by your web server user and that it is write/readable
 * Check that your installation fulfills the [requirements listed in the README section](https://github.com/nextcloud/news#dependencies)
-* [Set up Nextcloud Background Jobs](https://docs.nextcloud.org/server/latest/admin_manual/configuration_server/background_jobs_configuration.html#cron) to enable feed updates. A recommended timespan for feed updates is 15-30 Minutes.
+* [Set up Nextcloud Background Jobs](https://docs.nextcloud.org/server/latest/admin_manual/configuration_server/background_jobs_configuration.html#cron) to enable feed updates.
 
 Then proceed to install the app either from an archive (zip/tar.gz) or clone it from the repository using git