Move Downloads and HCL pages back to qubes-doc (#1267)

They won't show up in the index unless they're in qubes-doc.
https://groups.google.com/g/qubes-devel/c/ASj7tehn1G0/m/jhLmFjdMBwAJ

user/downloading-installing-upgrading/downloads.md

@@ -0,0 +1,11 @@
+---
+lang: en
+layout: site
+permalink: /downloads/
+redirect_from:
+- /doc/QubesDownloads/
+- /wiki/QubesDownloads/
+ref: 2
+title: Download Qubes OS
+---
+{% include downloads.html %}

user/hardware/hcl.md

@@ -0,0 +1,16 @@
+---
+lang: en
+layout: hcl
+model: all
+permalink: /hcl/
+redirect_from:
+- /doc/hcl/
+- /compatible-hardware/
+- /en/doc/hcl/
+- /doc/HCL/
+- /wiki/HCL/
+- /wiki/HCLR1/
+- /wiki/HCL-R2B2/
+ref: 143
+title: Hardware compatibility list (HCL)
+---