feat: add CSP (#84)

* feat: add CSP

* fix

* move to jekyll config

* fix

* add other options

* temp remove csp

* include headers

* add back csp

* Update _headers

Author: RoyalOughtness

_config.yaml

@@ -10,3 +10,4 @@ defaults:
       layout: "page"
 
 exclude: ["README.md"]
+include: ["_headers"]

_headers

@@ -0,0 +1,5 @@
+/*
+  X-Frame-Options: DENY
+  X-Content-Type-Options: nosniff
+  Referrer-Policy: no-referrer
+  Content-Security-Policy: default-src 'none'; style-src-elem 'self'; font-src 'self'; img-src 'self'; manifest-src 'self'; form-action 'none'; frame-ancestors 'none'; base-uri 'none'; sandbox; upgrade-insecure-requests;