Update the documentation about importing external certificates

modules/installation-guide/examples/snip_importing-untrusted-tls-certificates_1.adoc

@@ -0,0 +1,9 @@
+. Save the certificates you need to import, to a local file system.
++
+[CAUTION]
+====
+* Certificate files are typically stored as Base64 ASCII files, such as `.pem`, `.crt`, `.ca-bundle`. But, they can also be binary-encoded, for example, as `.cer` files. All Secrets that hold certificate files should use the Base64 ASCII certificate rather than the binary-encoded certificate.
+* {prod-short} already uses some reserved file names to automatically inject certificates into the ConfigMap, so you should avoid using the following reserved file names to save your certificates:
+  ** `ca-bundle.crt`
+  ** `ca.crt`
+====

modules/installation-guide/nav.adoc

@@ -41,7 +41,7 @@
 ** xref:deploying-che-with-support-for-git-repositories-with-self-signed-certificates.adoc[]
 ** xref:installing-che-using-storage-classes.adoc[]
 ** xref:configuring-storage-types.adoc[]
-** xref:importing-tls-certificates-to-che-server-java-truststore.adoc[]
+** xref:importing-untrusted-tls-certificates.adoc[]
 ** xref:switching-between-external-and-internal-communication.adoc[]
 
 * xref:upgrading-che.adoc[]

modules/installation-guide/pages/importing-untrusted-tls-certificates.adoc

@@ -0,0 +1,7 @@
+[id="importing-untrusted-tls-certificates"]
+// = Importing untrusted TLS certificates
+:navtitle: Importing untrusted TLS certificates to {prod-short}
+:keywords: installation-guide, tls, certificate
+:page-aliases: .:importing-untrusted-tls-certificates
+
+include::partial$proc_importing-untrusted-tls-certificates.adoc[]

modules/installation-guide/partials/assembly_advanced-configuration.adoc

@@ -32,7 +32,7 @@ The next sections describe some specific user stories.
 
 * xref:configuring-storage-types.adoc[]
 
-* xref:importing-tls-certificates-to-che-server-java-truststore.adoc[]
+* xref:importing-untrusted-tls-certificates.adoc[]
 
 * xref:switching-between-external-and-internal-communication.adoc[]