v4.1 (#11)

- Add `Json` module to return JSON strings and write JSON as it's read to a `PipeWriter`
- Add `docfx`-based documentation to allow how-to docs and API docs to be generated on the same site

Reviewed-on: #11

docs/toc.yml

@@ -0,0 +1,21 @@
+- name: Getting Started
+  href: getting-started.md
+- name: Basic Usage
+  href: basic-usage.md
+- name: Advanced Usage
+  href: advanced/index.md
+  items:
+    - name: Custom Serialization
+      href: advanced/custom-serialization.md
+    - name: Related Documents and Custom Queries
+      href: advanced/related.md
+    - name: Transactions
+      href: advanced/transactions.md
+- name: Upgrading
+  items:
+    - name: v3 to v4
+      href: upgrade/v4.md
+    - name: v2 to v3
+      href: upgrade/v3.md
+    - name: v1 to v2
+      href: upgrade/v2.md