Revert "Remove all instances of permalink: in YAML frontmatter"

This reverts commit c815e4c54c.

https://github.com/QubesOS/qubes-issues/issues/6701#issuecomment-862822827

developer/general/devel-books.md

@@ -1,8 +1,8 @@
 ---
 lang: en
 layout: doc
+permalink: /doc/devel-books/
 redirect_from:
-- /doc/devel-books/
 - /en/doc/devel-books/
 - /doc/DevelBooks/
 - /wiki/DevelBooks/

developer/general/doc-guidelines.md

@@ -1,8 +1,8 @@
 ---
 lang: en
 layout: doc
+permalink: /doc/doc-guidelines/
 redirect_from:
-- /doc/doc-guidelines/
 - /en/doc/doc-guidelines/
 - /wiki/DocStyle/
 - /doc/DocStyle/

developer/general/gsoc.md

@@ -1,8 +1,8 @@
 ---
 lang: en
 layout: sidebar
+permalink: /gsoc/
 redirect_from:
-- /gsoc/
 - /GSoC/
 ref: 33
 title: Google Summer of Code

developer/general/gsod.md

@@ -1,8 +1,7 @@
 ---
 lang: en
 layout: sidebar
-redirect_from:
-- /gsod/
+permalink: /gsod/
 ref: 242
 title: Google Season of Docs
 ---

developer/general/join.md

@@ -1,8 +1,7 @@
 ---
 lang: en
 layout: sidebar
-redirect_from:
-- /join/
+permalink: /join/
 ref: 26
 title: Join
 ---

developer/general/package-contributions.md

@@ -1,8 +1,7 @@
 ---
 lang: en
 layout: doc
-redirect_from:
-- /doc/package-contributions/
+permalink: /doc/package-contributions/
 ref: 29
 title: Package Contributions
 ---

developer/general/style-guide.md

@@ -1,8 +1,7 @@
 ---
 lang: en
 layout: doc
-redirect_from:
-- /doc/style-guide/
+permalink: /doc/style-guide/
 ref: 27
 title: Style-guide
 ---

developer/general/usability-ux.md

@@ -1,8 +1,7 @@
 ---
 lang: en
 layout: doc
-redirect_from:
-- /doc/usability-ux/
+permalink: /doc/usability-ux/
 ref: 31
 title: Usability & UX
 ---