docs: Render latest version on next branch

src/utils/getLatestVersion.js

 import axios from "axios";
 import semver from "semver";
 
-export default async function({ siteVersion, projectId }) {
-  return axios.get(`https://git.fitko.de/api/v4/projects/${projectId}/repository/tags`)
-    .catch((error) => {
-      throw `Fetching of latest tags failed with ${error.response.status}`
-    })
-    .then(async ({ data }) => {
-      if (siteVersion === 'next') {
-        return data[0].name
-      } else {
+export default async function ({siteVersion, projectId}) {
+  if (siteVersion === 'next') {
+    return 'latest'
+  } else {
+    return axios.get(`https://git.fitko.de/api/v4/projects/${projectId}/repository/tags`)
+      .catch((error) => {
+        throw `Fetching of latest tags failed with ${error.response.status}`
+      })
+      .then(async ({data}) => {
         const versionRange = `~${siteVersion}`
         const suitableVersions = await data
-          .filter(({ name }) => semver.satisfies(name, versionRange))
-          .map(({ name }) => name)
+          .filter(({name}) => semver.satisfies(name, versionRange))
+          .map(({name}) => name)
           .sort()
 
         return semver.maxSatisfying(suitableVersions, versionRange)
-      }
-    })
+      })
+  }
 }