style(git): add explainer to gitattributes file

This is in-line with a pull request also made to
a TypeScript starter template project, as seen below:
<stemmlerjs/simple-typescript-starter#43>

Author: freshgum-bubbles

.gitattributes

@@ -1,2 +1,5 @@
+# Fix how tsconfig.json files are displayed in GitHub's web view,
+# by telling it to read said files as JSON With Comments, the
+# JSON extension used by TypeScript.
 tsconfig.*.json linguist-language=JSON-with-Comments
 tsconfig.json linguist-language=JSON-with-Comments