Revise secrets-dir flag in the VC (#5480)

* Update docs on secrets-dir

* Hidden secrets-dir flag

* Remove conflicts_with

* Restore description

* make cli

* Update book/src/validator-management.md

account_manager/src/validator/create.rs

@@ -62,7 +62,6 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                     "The path where the validator keystore passwords will be stored. \
                     Defaults to ~/.lighthouse/{network}/secrets",
                 )
-                .conflicts_with("datadir")
                 .takes_value(true),
         )
         .arg(

book/src/validator-management.md

@@ -59,7 +59,9 @@ Each permitted field of the file is listed below for reference:
 - `voting_keystore_password`: The password to the EIP-2335 keystore.
 
 > **Note**: Either `voting_keystore_password_path` or `voting_keystore_password` *must* be
-> supplied. If both are supplied, `voting_keystore_password_path` is ignored.
+> supplied. If both are supplied, `voting_keystore_password_path` is ignored. 
+
+>If you do not wish to have  `voting_keystore_password` being stored in the `validator_definitions.yml` file, you can add the field `voting_keystore_password_path` and point it to a file containing the password. The file can be, e.g., on a mounted portable drive that contains the password so that no password is stored on the validating node. 
 
 ## Populating the `validator_definitions.yml` file
 
@@ -75,6 +77,7 @@ recap:
 
 ### Automatic validator discovery
 
+
 When the `--disable-auto-discover` flag is **not** provided, the validator client will search the
 `validator-dir` for validators and add any *new* validators to the
 `validator_definitions.yml` with `enabled: true`.

validator_client/src/cli.rs

@@ -73,7 +73,6 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                     key. Defaults to ~/.lighthouse/{network}/secrets.",
                 )
                 .takes_value(true)
-                .conflicts_with("datadir")
         )
         .arg(
             Arg::with_name("init-slashing-protection")