Docs: Enterprise Vault feature (#25895)

* Docs: Vault integration

* Add links to vault feature doc

* Update Enterprise configuration file with vault fields

* Small fixes on vault doc

* Update docs according to PR review

* Update docs/sources/administration/configuration.md

Co-authored-by: Leonard Gram <leo@xlson.com>

* Update docs/sources/enterprise/vault.md

Co-authored-by: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>

* Update docs/sources/enterprise/vault.md

Co-authored-by: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>

Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>
Co-authored-by: Leonard Gram <leo@xlson.com>
Co-authored-by: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>

docs/sources/enterprise/enterprise-configuration.md

@@ -186,3 +186,33 @@ List of comma- or space-separated roles that will be mapped to the Admin role.
 ### role_values_grafana_admin
 
 List of comma- or space-separated roles that will be mapped to the Grafana Admin (Super Admin) role.
+
+## [keystore.vault]
+
+### url
+
+Location of the Vault server.
+
+### namespace
+
+Vault namespace if using Vault with multi-tenancy.
+
+### auth_method
+
+Method for authenticating towards Vault. Vault is inactive if this option is not set. Current possible values: `token`.
+
+### token
+
+Secret token to connect to Vault when auth_method is `token`.
+
+### lease_renewal_interval
+
+Time between checking if there are any secrets which needs to be renewed.
+
+### lease_renewal_expires_within
+
+Time until expiration for tokens which are renewed. Should have a value higher than lease_renewal_interval.
+
+### lease_renewal_increment
+
+New duration for renewed tokens. Vault may be configured to ignore this value and impose a stricter limit.