Fix README to document separate resources for random secrets and keypairs

[Copilot]

The README incorrectly described vaultprov_random_secret with a type field supporting both random_secret and curve25519_keypair. The actual implementation uses two separate resources.

Changes:

• Updated README to document vaultprov_random_secret and vaultprov_keypair_secret as separate resources
• Corrected vaultprov_random_secret examples to remove non-existent type parameter
• Corrected vaultprov_keypair_secret examples to use base_path instead of path
• Clarified that keypairs are stored as two separate Vault secrets (/base_path/private and /base_path/public), not concatenated

Before:

resource "vaultprov_random_secret" "my_keypair" {
  path = "/secrets/bar/foo"
  type = "curve25519_keypair"  # Wrong resource and parameter
  metadata = { ... }
}

After:

resource "vaultprov_keypair_secret" "my_keypair" {
  base_path = "/secrets/bar/foo"
  type      = "curve25519"
  metadata  = { ... }
}

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• checkpoint-api.hashicorp.com
  • Triggering command: /tmp/go-build365712177/b001/exe/tfplugindocs /tmp/go-build365712177/b001/exe/tfplugindocs generate --provider-name vaultprov -goversion go1.25.7 -c=4 -nolocalimports -importcfg /tmp/go-build365712177/b245/importcfg -pack lude conf�� 0.1-go1.25.7.lin-pthread ux-amd64/src/net-Wl,--no-gc-sections rg/toolchain@v0.-fmessage-length=0 user.email (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

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