feat: introduce "jsdoc" dependency

This is step 1 of adopting "jsdoc" for documentation, which
*only* introduces the dependency, updates the .gitignore,
and applies basic configuration so we can use Markdown in jsdoc
comments.

This includes no actual documentation, which will be added next.

Signed-off-by: Andrew Lilley Brinker <abrinker@mitre.org>

Author: alilleybrinker

.gitignore

@@ -104,3 +104,5 @@ commit-message.txt
 # configuration) and provide an example instead
 docker/.docker-env
 
+# Generated jsdoc documentation
+jsdoc/

.jsdoc.json

@@ -0,0 +1,3 @@
+{
+    "plugins": ["plugins/markdown"]
+}