Replace X-Robots-Tag header value with "noindex, nofollow"

For reference: nextcloud/server#36689

Signed-off-by: MichaIng <micha@dietpi.com>

Author: MichaIng

admin_manual/installation/harden_server.rst

@@ -197,8 +197,8 @@ These include:
 	- Instructs some browsers to not sniff the mimetype of files. This is used for example to prevent browsers from interpreting text files as JavaScript.
 - ``X-XSS-Protection: 1; mode=block``
 	- Instructs browsers to enable their browser side Cross-Site-Scripting filter.
-- ``X-Robots-Tag: none``
-	- Instructs search machines to not index these pages.
+- ``X-Robots-Tag: noindex, nofollow``
+	- Instructs search machines to not index these pages and not follow any links there.
 - ``X-Frame-Options: SAMEORIGIN``
 	- Prevents embedding of the Nextcloud instance within an iframe from other domains to prevent Clickjacking and other similar attacks.
 - ``Referrer-Policy: no-referrer``

admin_manual/installation/nginx-root.conf.sample

@@ -69,13 +69,13 @@ server {
     client_body_buffer_size 512k;
 
     # HTTP response headers borrowed from Nextcloud `.htaccess`
-    add_header Referrer-Policy                      "no-referrer"   always;
-    add_header X-Content-Type-Options               "nosniff"       always;
-    add_header X-Download-Options                   "noopen"        always;
-    add_header X-Frame-Options                      "SAMEORIGIN"    always;
-    add_header X-Permitted-Cross-Domain-Policies    "none"          always;
-    add_header X-Robots-Tag                         "none"          always;
-    add_header X-XSS-Protection                     "1; mode=block" always;
+    add_header Referrer-Policy                   "no-referrer"       always;
+    add_header X-Content-Type-Options            "nosniff"           always;
+    add_header X-Download-Options                "noopen"            always;
+    add_header X-Frame-Options                   "SAMEORIGIN"        always;
+    add_header X-Permitted-Cross-Domain-Policies "none"              always;
+    add_header X-Robots-Tag                      "noindex, nofollow" always;
+    add_header X-XSS-Protection                  "1; mode=block"     always;
 
     # Remove X-Powered-By, which is an information leak
     fastcgi_hide_header X-Powered-By;

admin_manual/installation/nginx-subdir.conf.sample

@@ -92,13 +92,13 @@ server {
         client_body_buffer_size 512k;
 
         # HTTP response headers borrowed from Nextcloud `.htaccess`
-        add_header Referrer-Policy                      "no-referrer"   always;
-        add_header X-Content-Type-Options               "nosniff"       always;
-        add_header X-Download-Options                   "noopen"        always;
-        add_header X-Frame-Options                      "SAMEORIGIN"    always;
-        add_header X-Permitted-Cross-Domain-Policies    "none"          always;
-        add_header X-Robots-Tag                         "none"          always;
-        add_header X-XSS-Protection                     "1; mode=block" always;
+        add_header Referrer-Policy                   "no-referrer"       always;
+        add_header X-Content-Type-Options            "nosniff"           always;
+        add_header X-Download-Options                "noopen"            always;
+        add_header X-Frame-Options                   "SAMEORIGIN"        always;
+        add_header X-Permitted-Cross-Domain-Policies "none"              always;
+        add_header X-Robots-Tag                      "noindex, nofollow" always;
+        add_header X-XSS-Protection                  "1; mode=block"     always;
 
         # Remove X-Powered-By, which is an information leak
         fastcgi_hide_header X-Powered-By;