[Feature] Add IndexMethod docs (#1437)

Author: ajanikow

CHANGELOG.md

@@ -8,6 +8,7 @@
 - (Bugfix) Fix numactl options
 - (Maintenance) Bump Go to 1.20.10
 - (Bugfix) Fix ArangoBackup Create Backoff & ArangoBackupPolicy propagation
+- (Maintenance) Add IndexMethod Documentation
 
 ## [1.2.33](https://github.com/arangodb/kube-arangodb/tree/1.2.33) (2023-09-27)
 - (Maintenance) Bump golang.org/x/net to v0.13.0