Minor API Key Readme Update (#286)

* moved doc for setting env var to new line

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* removed export

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: sdhoyt

README.md

@@ -143,13 +143,14 @@ To use the API Key you can set the `IMAP_API_KEY` environment variable and then
 the tool as usual.
 
 ```bash
-IMAP_API_KEY=<your-api-key> imap-data-access ...
+$ IMAP_API_KEY=<your-api-key>
+$ imap-data-access ...
 ```
 
 or with CLI flags
 
 ```bash
-imap-data-access --api-key <your-api-key> ...
+$ imap-data-access --api-key <your-api-key> ...
 ```
 
 ### Automated use with Access token