Merge pull request #4107 from backstage/jhaals/credentials-suffix

cli: Append '-credentials' to file generated by create-github-app

.changeset/loud-kids-dance.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Append `-credentials.yaml` to credentials file generated by `backstage-cli create-github-app` and display warning about sensitive contents.

.changeset/spoon-fork.md

@@ -0,0 +1,12 @@
+---
+'@backstage/create-app': patch
+---
+
+Add `*-credentials.yaml` to gitignore to prevent accidental commits of sensitive credential information.
+
+To apply this change to an existing installation, add these lines to your `.gitignore`
+
+```gitignore
+# Sensitive credentials
+*-credentials.yaml
+```