qr: add page (#3769)

* qr: add page

* Update qr.md

pages/common/qr.md

@@ -0,0 +1,12 @@
+# qr
+
+> Generate QR codes in the terminal with ANSI VT-100 escape codes.
+> More information: <https://github.com/lincolnloop/python-qrcode/>.
+
+- Generate a QR code:
+
+`echo "{{data}}" | qr`
+
+- Specify the error correction level (defaults to M):
+
+`echo "{{data}}" | qr --error-correction={{L|M|Q|H}}`