Shows html instead of raw markdown on CSS

[angelo-v]

CSS delivers a html rendering of markdown files by default, which causes the pane and textarea to include this html code instead of the raw markdown content. The pane needs to explicitly request "text/markdown"

[angelo-v]

see #6 (comment)

[josephguillaume]

In case anybody else chances upon this, the default behaviour from CSS can also be changed by overriding the config files to remove the markdown to html converter in https://github.com/CommunitySolidServer/CommunitySolidServer/blob/17d0413923cee27ee017b19d372be7e1da8fd365/config/util/representation-conversion/default.json