Add Gentoo template related

- Specific release note will follow later

QubesOS/qubes-issues#4412

user/managing-os/minimal-templates.md

@@ -16,7 +16,7 @@ redirect_from:
 The Minimal [TemplateVMs] are lightweight versions of their standard TemplateVM counterparts.
 They have only the most vital packages installed, including a minimal X and xterm installation.
 The sections below contain instructions for using the template and provide some examples for common use cases.
-There are currently three Minimal TemplateVMs corresponding to the standard [Fedora], [Debian] and [CentOS] TemplateVMs.
+There are currently three Minimal TemplateVMs corresponding to the standard [Fedora], [Debian], [CentOS] and [Gentoo] TemplateVMs.
 
 
 ## Important
@@ -216,6 +216,7 @@ You could, of course, use `qubes-vm-recommended` to automatically install many o
 [Fedora]: /doc/templates/fedora/
 [Debian]: /doc/templates/debian/
 [CentOS]: /doc/templates/centos/
+[Gentoo]: /doc/templates/gentoo/
 [Help, Support, Mailing Lists, and Forum]: /support/
 [doc-guidelines]: /doc/doc-guidelines/
 [pref-default]: /faq/#could-you-please-make-my-preference-the-default

user/managing-os/templates.md

@@ -62,6 +62,10 @@ In addition, these templates may be somewhat less stable, since the Qubes develo
  * [Arch Linux]
  * [CentOS]
  * [CentOS Minimal]
+ * [CentOS Xfce]
+ * [Gentoo]
+ * [Gentoo Minimal]
+ * [Gentoo Xfce]
 
 ## Installing