Main update (#1612)

* Render the example helpful tip properly. (#1586)

* Render the example helpful tip properly.

* Fix note syntax, again.

* Update rdf-mapping.md doc (#1585)

Co-authored-by: Eli Zoller <5439169+elizoller@users.noreply.github.com>

docs/contributing/docs_style_guide.md

@@ -10,9 +10,20 @@
 - Use `-` instead of `*` for bulleted lists.
 - Upload images to the 'assets' folder and reference them from there. 
    -- For file name, use underscores between words and prefix all file names with the page name, e.g. context_display_hints.jpg for the image showing how to set display hints in the context menu.
-- Use `!!! note  "Note title"` at the start of a paragraph to have it rendered as a note like this:
+- Use the [Admonition syntax](https://squidfunk.github.io/mkdocs-material/reference/admonitions/) to create notes like this (four-space indent required):
+
+_Example:_
+
+```
+!!! note "Helpful Tip" 
+    I am a helpful tip!
+```
+
+_Result:_
+
+!!! note "Helpful Tip" 
+    I am a helpful tip!
 
-!!! note "Helpful Tip" I am a helpful tip!
 
 ## Don'ts
 

docs/islandora/rdf-mapping.md

@@ -63,8 +63,28 @@ Below is an example of an RDF mapping as a .yml (YAML) file. It is the current v
 
 - The top level key `types` specifies the `rdf:type` of the resource or content model. `field_model`, a required field of Islandora objects, also gets mapped to `rdf:type` through an arcane back-end process.
 - The top level key `fieldMappings` specifies fields attached to that bundle and their RDF property mappings. One field can be mapped to more than one RDF property. It is a simple flat list.
-- `datatype_callback` : [needs documentation]
-- `mapping_type: rel` : [needs documentation]
+
+#### Mapping Types
+`mapping_type:`: There are several mapping types which are provided out of the box.
+- `rel` - standing for relationship, expresses a relationship between two resources
+- `property` - the default, or if a relationship is not provided, expresses the relationship between a resource and some literal text.
+
+#### Datatype Callbacks
+`datatype_callback`: This is a custom function that transforms the output of the field. There are some provided to us by Drupal and some added by Islandora, such as:
+- `Drupal\controlled_access_terms\EDTFConverter::dateIso8601Value` which converts dates to Iso format
+- `Drupal\jsonld\EntityReferenceConverter::linkFieldPassthrough` which converts a referenced entity to the URI on the entity (which is configurable with the `link_field` argument
+An example usage of the `Drupal\jsonld\EntityReferenceConverter::linkFieldPassthrough` is as follows:
+```yml
+field_subject:
+    properties:
+      - 'dcterms:subject'
+    datatype_callback:
+      callable: 'Drupal\jsonld\EntityReferenceConverter::linkFieldPassthrough'
+      arguments:
+        link_field: 'field_authority_link'
+```
+Which would convert a reference to the subject's taxonomy term entity to a reference to the URI provided in `field_authority_link` of that subject's taxonomy term entity.
+
 
 ## Sample RDF Mapping
 ```yml