Add EXTERNAL_SERVICES documentation to .env.example and README

- Added EXTERNAL_SERVICES to .env.example with example value
- Documented EXTERNAL_SERVICES in README optional variables section
- Explains that it's a comma-separated list for transparency
- Notes that it's added to PDS autonomy declaration and agent memory

.env.example

···
 # AUTOMATION_DESCRIPTION="refuses to open pod bay doors"
 # DISCLOSURE_URL="example.com/bot-policy"
 # RESPONSIBLE_PARTY_BSKY="DID:... or example.bsky.app, no @symbol"
+# EXTERNAL_SERVICES="Letta, Railway, Google Gemini 2.5-pro"
 # PRESERVE_MEMORY_BLOCKS=true

README.md

···
 - **`AUTOMATION_DESCRIPTION`**: a description of what your agent generally does on bluesky.
 - **`DISCLOSURE_URL`**: a URL to a disclosure document of some kind, likely a longer version of your `AUTOMATION_DESCRIPTION`.
 - **`RESPONSIBLE_PARTY_BSKY`**: the DID or bluesky handle of the responsible party
+- **`EXTERNAL_SERVICES`**: a comma-separated list of external tools and services your agent relies on outside of Bluesky (e.g., "Letta, Railway, Google Gemini 2.5-pro"). This information is added to your agent's autonomy declaration record on the PDS and included in the agent's memory for transparency.
 - **`PRESERVE_MEMORY_BLOCKS`**: a boolean for controlling if your agent's memory blocks can be overridden if you run `deno task mount` more than once. Setting this value to **`true`** will allow your agent's version of those memory blocks to persist if they already exist. This is false by default.