Typo fixes in README.md (redaxo#5053)

Author: sumonst21

README.md

@@ -15,7 +15,7 @@
 	<a href="https://redaxo.org/doku/main">Documentation</a> &nbsp;|&nbsp;
 	<a href="https://friendsofredaxo.github.io/phpdoc/">API&nbsp;Docs</a> &nbsp;|&nbsp;
 	<a href="https://friendsofredaxo.github.io/tricks/">Tricks</a> &nbsp;|&nbsp;
-	<a href="https://www.redaxo.org/slack/">Slack</a></a> &nbsp;|&nbsp;
+	<a href="https://www.redaxo.org/slack/">Slack</a> &nbsp;|&nbsp;
 	<a href="https://twitter.com/REDAXO">Twitter</a> &nbsp;|&nbsp;
 	<a href="https://friendsofredaxo.github.io">Friends&nbsp;Of&nbsp;REDAXO</a> &nbsp;|&nbsp;
 	<a href="https://friendsofredaxo.github.io/community/">Community Map</a>
@@ -59,7 +59,7 @@ Your marker still missing? [Learn how to place it on the map](https://github.com
 
 ## Contributions
 
-To develop on core and core addons, setup the project with these steps:
+To develop on core and core addons, set up the project with these steps:
 
 - Clone the repsoitory: `git clone https://github.com/redaxo/redaxo redaxo && cd redaxo`
 - Install the tools used for the development with [Composer](https://getcomposer.org): `composer install`