add note about NATS env vars to readme

Author: williamstein

src/README.md

@@ -64,7 +64,6 @@ If you export the PORT environment variable, that determines what port everythin
 
 CoCalc also runs a NATS server listening on two ports on localhost, one for TCP and one for WebSocket connections.  To avoid conflicts, you can customize their ports by setting the environment variables `COCALC_NATS_PORT` (default 4222), and `COCALC_NATS_WS_PORT` (default 8443).
 
-
 **Note**: If you installed `pnpm` locally (instead of globally), simply run `npm run` in place of `pnpm` to execute
 these commands via [NPM run scripts](https://docs.npmjs.com/cli/v10/using-npm/scripts).
 
@@ -144,7 +143,7 @@ You can also just type `pnpm psql` :
 ~/cocalc/src$ pnpm psql
 ```
 
-NOTE:  As of Jan 2023, CoCalc should fully work with any version of PostgreSQL from version 10.x onward.  However, obviously at some point we will stop supporting PostgreSQL v 10.
+NOTE:  As of Jan 2023, CoCalc should fully work with any version of PostgreSQL from version 14.x onward.  However, obviously at some point we will stop supporting PostgreSQL v 14.
 
 ### 2. More about Starting the Hub
 
@@ -186,6 +185,14 @@ which installs exactly the right packages, and builds the code.
 
 See `packages/backend/data.ts` . In particular, you can set BASE_PATH, DATA, PGHOST, PGDATA, PROJECTS, SECRETS to override the defaults. Data is stored in `cocalc/src/data/` by default.
 
+For NATS when doing development, it can be useful to set these in .bashrc so NATS uses ports of your choosing that are available.
+
+```sh
+export COCALC_NATS_SERVER_NAME=localhost
+export COCALC_NATS_PORT=5007
+export COCALC_NATS_WS_PORT=5008
+```
+
 #### File System Build Caching
 
 There are two types of file system build caching. These greatly improve the time to compile typescript or start webpack between runs. However, in rare cases bugs may lead to weird broken behavior. Here's where the caches are, so you know how to clear them to check if this is the source of trouble. _As of now, I'm_ _**not**_ _aware of any bugs in file system caching._