Clarify that LDAP will create Grafana users by default when they log in for the first time (#63391)

* Clarify that enabling LDAP will create users by default when they log in

This proposed change to the doc was requested by a user in support ticket `79860`, as it was not clear to them that the OOTB behavior was for user accounts to be provisioned automatically in Grafana when signing in for the first time via LDAP.

* Update docs/sources/setup-grafana/configure-security/configure-authentication/ldap/index.md

Thanks!

Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

* fix boolean

Woops, `true` should be `false`

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Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

docs/sources/setup-grafana/configure-security/configure-authentication/ldap/index.md

@@ -27,6 +27,8 @@ This means that you should be able to configure LDAP integration using any compl
 In order to use LDAP integration you'll first need to enable LDAP in the [main config file]({{< relref "../../../configure-grafana/" >}}) as well as specify the path to the LDAP
 specific configuration file (default: `/etc/grafana/ldap.toml`).
 
+After enabling LDAP, the default behavior is for Grafana users to be created automatically upon successful LDAP authentication. If you prefer for only existing Grafana users to be able to sign in, you can change `allow_sign_up` to `false` in the `[auth.ldap]` section.
+
 ```ini
 [auth.ldap]
 # Set to `true` to enable LDAP integration (default: `false`)