Comment out the postgres configuration from .env.template (#502)

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## Description
Simplest cognee docker setup of SQLite-NetworkX-LanceDB should not
enable postgres configuration in the .env.template by default. I think
leaving postgres details commented is better than removing them
entirely. This keeps simple optionality visible for newcomers.

## DCO Affirmation
I affirm that all code in every commit of this pull request conforms to
the terms of the Topoteretes Developer Certificate of Origin



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Chores**
- Updated configuration template to remove database parameters not used
in the default setup, with clearer guidance to ensure the intended
configuration is maintained.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.env.template

@@ -42,8 +42,8 @@ DB_PROVIDER="sqlite"
 # Database name
 DB_NAME=cognee_db
 
-# Postgres specific parameters (Only if Postgres or PGVector is used)
-DB_HOST=127.0.0.1
-DB_PORT=5432
-DB_USERNAME=cognee
-DB_PASSWORD=cognee
+# Postgres specific parameters (Only if Postgres or PGVector is used). Do not use for cognee default simplest setup of SQLite-NetworkX-LanceDB
+# DB_HOST=127.0.0.1
+# DB_PORT=5432
+# DB_USERNAME=cognee
+# DB_PASSWORD=cognee