Improve code diff rendering styles (#184)

* Update update docusaurus to canary version to allow for starting codeblock line number to be set

* Add start/end magic comments for diffs so each line does not need to be individually annotated

* Fix alignment issues when diffs and line numbers are displayed at the same time

* Replace default space character with empty string

* Refactor styles

Author: thgaskell

docusaurus.config.js

@@ -561,12 +561,20 @@ ${content}`,
         darkTheme: prismThemes.dracula,
         magicComments: [
           {
-            className: 'code-block-diff-add-line',
-            line: 'diff-add'
+            className: "code-block-diff-add-line",
+            line: "diff-add",
+            block: {
+              start: "diff-add-start",
+              end: "diff-add-end"
+            }
           },
           {
-            className: 'code-block-diff-remove-line',
-            line: 'diff-remove'
+            className: "code-block-diff-remove-line",
+            line: "diff-remove",
+            block: {
+              start: "diff-remove-start",
+              end: "diff-remove-end"
+            }
           }
         ]
       },