docs: merge plugin-related navigation items (#5655) [ci skip]

Author: gtsiolis

docs/.vuepress/config.js

@@ -72,20 +72,47 @@ module.exports = {
             text: 'Config Reference',
             link: '/config/'
           },
-          {
-            text: 'Plugin Dev Guide',
-            items: [
-              { text: 'Plugin Dev Guide', link: '/dev-guide/plugin-dev.md' },
-              { text: 'UI Plugin Info', link: '/dev-guide/ui-info.md' },
-              { text: 'UI Plugin API', link: '/dev-guide/ui-api.md' },
-              { text: 'UI Localization', link: '/dev-guide/ui-localization.md' }
-            ]
-          },
           {
             text: 'Plugins',
             items: [
-              { text: 'Core plugins', link: '/core-plugins/' },
-              { text: 'Browse plugins', link: 'https://awesomejs.dev/for/vue-cli/' }
+              {
+                text: 'Configuration',
+                items:
+                [
+                  { text: 'Core', link: '/core-plugins/' },
+                ]
+              },
+              {
+                text: 'Discover',
+                items:
+                [
+                  { text: 'Browse', link: 'https://awesomejs.dev/for/vue-cli/' }
+                ]
+              },
+              {
+                text: 'Development',
+                items:
+                [
+                  { text: 'Guide', link: '/dev-guide/plugin-dev.md' },
+                ]
+              },
+              {
+                text: 'API',
+                items:
+                [
+                  { text: 'Plugin', link: '/dev-guide/plugin-api.md' },
+                  { text: 'Generator', link: '/dev-guide/generator-api.md' },
+                ]
+              },
+              {
+                text: 'UI',
+                items:
+                [
+                  { text: 'Info', link: '/dev-guide/ui-info.md' },
+                  { text: 'API', link: '/dev-guide/ui-api.md' },
+                  { text: 'Localization', link: '/dev-guide/ui-localization.md' }
+                ]
+              },
             ]
           },
           {