Add and augment conceptual docs (#1375)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Mike Kistler <mikekistler@microsoft.com>
Co-authored-by: Stephen Toub <stoub@microsoft.com>
Co-authored-by: Stephen Halter <halter73@gmail.com>

docs/concepts/toc.yml

@@ -3,16 +3,36 @@ items:
   href: index.md
 - name: Base Protocol
   items:
+  - name: Capabilities
+    uid: capabilities
+  - name: Transports
+    uid: transports
+  - name: Ping
+    uid: ping
   - name: Progress
     uid: progress
+  - name: Cancellation
+    uid: cancellation
+  - name: Pagination
+    uid: pagination
   - name: Tasks
     uid: tasks
 - name: Client Features
   items:
+  - name: Roots
+    uid: roots
   - name: Elicitation
     uid: elicitation
 - name: Server Features
   items:
+  - name: Tools
+    uid: tools
+  - name: Resources
+    uid: resources
+  - name: Prompts
+    uid: prompts
+  - name: Completions
+    uid: completions
   - name: Logging
     uid: logging
   - name: HTTP Context