docs: add missing sidebar navigation entries

Add recently created docs to the navigation sidebar:

Commands:
- add (transaction entry)
- config (configuration management)

Guides:
- Custom Plugins (WASM/native plugin development)
- Embedding rustledger (CLI, WASM, WASI, LSP integration)

Development:
- Contributing Plugins (plugin contribution guide)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: robcohen

docs/.vitepress/config.js

@@ -50,8 +50,10 @@ export default defineConfig({
                         { text: 'Common Queries', link: '/guides/common-queries' },
                         { text: 'Budgeting', link: '/guides/budgeting' },
                         { text: 'Importing Data', link: '/guides/importing' },
+                        { text: 'Custom Plugins', link: '/guides/custom-plugins' },
                         { text: 'Shell Aliases', link: '/guides/shell-aliases' },
                         { text: 'Editor Integration', link: '/guides/editor-integration' },
+                        { text: 'Embedding rustledger', link: '/guides/integration' },
                         { text: 'Multi-file Ledgers', link: '/guides/multi-file' },
                     ],
                 },
@@ -76,6 +78,8 @@ export default defineConfig({
                         { text: 'format', link: '/commands/format' },
                         { text: 'extract', link: '/commands/extract' },
                         { text: 'price', link: '/commands/price' },
+                        { text: 'add', link: '/commands/add' },
+                        { text: 'config', link: '/commands/config' },
                         { text: 'doctor', link: '/commands/doctor' },
                     ],
                 },
@@ -100,6 +104,7 @@ export default defineConfig({
                         { text: 'Overview', link: '/development/' },
                         { text: 'Testing', link: '/development/testing' },
                         { text: 'Benchmarking', link: '/development/benchmarking' },
+                        { text: 'Contributing Plugins', link: '/development/contributing-plugins' },
                     ],
                 },
             ],