Update go-kms-wrapping for OpenBao brand consistency

[aj-geddes]

Problem

README.md contains HashiCorp repository references and Vault references that should point to OpenBao equivalents.

Proposed Changes

• Update GitHub repository references from hashicorp/go-kms-wrapping to openbao/go-kms-wrapping
• Change documentation links to openbao.org where appropriate
• Update user-facing "Vault" references to "OpenBao" (e.g., "Vault's auto-unseal" → "OpenBao's auto-unseal")
• Correct installation instructions to use OpenBao repository

Benefits

• Consistent branding across OpenBao ecosystem
• Correct documentation links for users
• Professional project presentation