[8.x] [Stateful sidenav] Update docs (elastic#193988) (elastic#194124)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[Stateful sidenav] Update docs
(elastic#193988)](elastic#193988)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Sébastien
Loix","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-09-26T12:17:56Z","message":"[Stateful
sidenav] Update docs
(elastic#193988)","sha":"650c730c209743779e5c8980311693d1e3e117eb","branchLabelMapping":{"^v9.0.0$":"main","^v8.16.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","v9.0.0","docs","Team:SharedUX","backport:prev-minor"],"title":"[Stateful
sidenav] Update
docs","number":193988,"url":"https://github.com/elastic/kibana/pull/193988","mergeCommit":{"message":"[Stateful
sidenav] Update docs
(elastic#193988)","sha":"650c730c209743779e5c8980311693d1e3e117eb"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.0.0","branchLabelMappingKey":"^v9.0.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/193988","number":193988,"mergeCommit":{"message":"[Stateful
sidenav] Update docs
(elastic#193988)","sha":"650c730c209743779e5c8980311693d1e3e117eb"}}]}]
BACKPORT-->

Co-authored-by: Sébastien Loix <[email protected]>

dev_docs/nav-kibana-dev.docnav.json

@@ -222,7 +222,7 @@
           "id": "ktCustomServerlessImage"
         },
         {
-          "id": "kibDevTutorialsServerlessProjectNavigation"
+          "id": "kibDevTutorialsSolutionNavigation"
         }
       ]
     },
@@ -240,8 +240,8 @@
       "pageId": "kibDevDocsSharedUxOverview",
       "items": [
         {
-          "label": "Serverless Project Navigation",
-          "id": "kibDevTutorialsServerlessProjectNavigation"
+          "label": "Solution Navigation (stateful solution nav and serverless navigation",
+          "id": "kibDevTutorialsSolutionNavigation"
         },
         {
           "id": "kibDevTutorialFileService",