Don't access pgp.mit.edu over HTTP

docs/reference/setup/repositories.asciidoc

@@ -8,12 +8,12 @@ build.
 We have split the major versions in separate urls to avoid accidental upgrades across major version.
 For all 0.90.x releases use 0.90 as version number, for 1.0.x use 1.0, for 1.1.x use 1.1 etc.
 
-We use the PGP key http://pgp.mit.edu/pks/lookup?op=vindex&search=0xD27D666CD88E42B4[D88E42B4],
+We use the PGP key https://pgp.mit.edu/pks/lookup?op=vindex&search=0xD27D666CD88E42B4[D88E42B4],
 Elasticsearch Signing Key, with fingerprint
 
     4609 5ACC 8548 582C 1A26 99A9 D27D 666C D88E 42B4
 
-to sign all our packages. It is available from http://pgp.mit.edu.
+to sign all our packages. It is available from https://pgp.mit.edu.
 
 [float]
 === APT