Add links to changelog
## ChangeLog
### New Features
-* Enables ability to migrate to Configurable Security Policies (CSP) on a per agent basis for accounts already using High Security Mode (HSM).
+* Enables ability to migrate to [Configurable Security Policies (CSP)](https://docs.newrelic.com/docs/agents/manage-apm-agents/configuration/enable-configurable-security-policies) on a per agent basis for accounts already using [High Security Mode (HSM)](https://docs.newrelic.com/docs/agents/manage-apm-agents/configuration/high-security-mode).
* Previously, if CSP was configured for an account, New Relic would not allow an agent to connect without the `security_policies_token`. This led to agents not being able to connect during the period between when CSP was enabled for an account and when each agent is configured with the correct token.
* With this change, when both HSM and CSP are enabled for an account, an agent (this version or later) can successfully connect with either `high_security: true` or the appropriate `security_policies_token` configured - allowing the agent to continue to connect after CSP is configured on the account but before the appropriate `security_policies_token` is configured for each agent.
