For dark color schemes in eclipse, the default markdown colors are hard to read. This makes it difficult to edit README.md files, for example.
It took me a while to find the right setting to change font color and thought I would share the answer.
In Eclipse, open:
Window > Preferences > General > Editors > Text Editors > WikiText
Select "WikiText", not any of the subfolders.
From here, there are inputs where you can change the color style. For example:
color: #ccc;
You must close and restart Eclipse for the settings to take effect.
There appears to be a bug in WikiText > Appearance, as changes made there did not take effect for me.