Not every company has a #security channel in slack/irc

For us, in @alphagov, our #security channel is for physical security questions and our cyber security team hang out in #cybersecurity.

This seems like the simplest way to get the message changed, working even for people who don't - or can't - use a config.

My edits formatted with [black](https://github.com/psf/black)
For example

detect_secrets/pre_commit_hook.py

@@ -1,6 +1,7 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
+import os
 import subprocess
 import sys
 import textwrap
@@ -205,12 +206,15 @@ def _print_secrets_found(secrets):
 
 
 def _print_mitigation_suggestions():
+    security_team = os.environ.get("DETECT_SECRETS_SECURITY_TEAM", "in #security")
     suggestions = [
-        'For information about putting your secrets in a safer place, please ask in #security',
-        'Mark false positives with an inline `pragma: allowlist secret` comment',
-        'Commit with `--no-verify` if this is a one-time false positive',
+        "For information about putting your secrets in a safer place, please ask "
+        + security_team,
+        "Mark false positives with an inline `pragma: allowlist secret` comment",
+        "Commit with `--no-verify` if this is a one-time false positive",
     ]
 
+
     wrapper = textwrap.TextWrapper(
         initial_indent='  - ',
         subsequent_indent='    ',