Update links in docs pages

Author: kndehaan

docs/contrib/authoring-docs.md

@@ -2,7 +2,7 @@
 title: Writing documentation
 ---
 
-When adding new features to the ETM, documenation should be written so that users understand how to use the new feature, and fellow modellers and developers understand how it works as well. Note that the [guidelines for writing texts](./authoring-text-guidelines.md) should be followed when writing documentation.
+When adding new features to the ETM, documenation should be written so that users understand how to use the new feature, and fellow modellers and developers understand how it works as well. Note that the [guidelines for writing texts](./authoring-texts.md) should be followed when writing documentation.
 
 ## Getting started
 

docs/contrib/authoring-slider-texts.md

@@ -2,7 +2,7 @@
 title: Writing slider descriptions
 ---
 
-Sliders are the visual representation of [Inputs](inputs.md) in the ETM. Modellers can add a description to sliders. This description becomes visible when users select the information button presented as a question mark next to each slider. For clarity, it is important that all slider descriptions follow the same structure and writing style. The [guidelines for writing texts](./authoring-text-guidelines.md) should be followed when writing slider descriptions.
+Sliders are the visual representation of [Inputs](inputs.md) in the ETM. Modellers can add a description to sliders. This description becomes visible when users select the information button presented as a question mark next to each slider. For clarity, it is important that all slider descriptions follow the same structure and writing style. The [guidelines for writing texts](./authoring-texts.md) should be followed when writing slider descriptions.
 
 ## Guidelines
 A good slider description contains the following aspects: