Add instructions for running mdbook linkcheck (#238)

* Update config to support linkcheck

Allows checking if all relative links inside the mdBook are valid.
Especially useful for ensuring updated links when moving content around.


* Add section explaining link check to readme

1 files changed, 5 insertions, 0 deletions

diff --git a/book.toml b/book.toml
index b788c8a..b4b3256 100644
--- a/book.toml
+++ b/book.toml
@@ -6,3 +6,8 @@ language = "en"
 multilingual = false
 src = "docs"
 title = "Northstar Wiki"
+
+[output.html]
+
+[output.linkcheck]
+optional = true