standardize spacing between sections

README.md

@@ -306,7 +306,6 @@ _Related: [Groupware](#groupware)_
 
 _See also: [Comparison of CalDAV and CardDAV implementations - Wikipedia](https://en.wikipedia.org/wiki/Comparison_of_CalDAV_and_CardDAV_implementations)_
 
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 - [Baïkal](https://sabre.io/baikal/) - Lightweight CalDAV and CardDAV server based on sabre/dav. ([Source Code](https://github.com/sabre-io/Baikal)) `GPL-3.0` `PHP`
 - [calypso](https://keithp.com/calypso/) - Python-based CalDAV and CardDAV server, forked from Radicale. ([Source Code](https://keithp.com/cgit/)) `GPL-3.0` `Python`
 - [DAViCal](https://www.davical.org/) - Server for calendar sharing (CalDAV) that uses a PostgreSQL database as a data store. ([Source Code](https://gitlab.com/davical-project/davical)) `GPL-2.0` `PHP`
@@ -2162,7 +2161,6 @@ _See also: [Wikimatrix](https://www.wikimatrix.org/), [Wiki Engines - WikiIndex]
 - `Zlib` - [Zlib/libpng License](https://spdx.org/licenses/Zlib.html)
 - `ZPL-2.0` - [Zope Public License 2.0](https://spdx.org/licenses/ZPL-2.0.html)
 
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 ## Anti-features