[trivial][doc] Use Debian 8.5 in the gitian-build guide

doc/gitian-building.md

@@ -1,7 +1,7 @@
 Gitian building
 ================
 
-*Setup instructions for a Gitian build of Bitcoin using a Debian VM or physical system.*
+*Setup instructions for a Gitian build of Bitcoin Core using a Debian VM or physical system.*
 
 Gitian is the deterministic build process that is used to build the Bitcoin
 Core executables. It provides a way to be reasonably sure that the
@@ -26,7 +26,7 @@ Table of Contents
 - [Installing Gitian](#installing-gitian)
 - [Setting up the Gitian image](#setting-up-the-gitian-image)
 - [Getting and building the inputs](#getting-and-building-the-inputs)
-- [Building Bitcoin](#building-bitcoin)
+- [Building Bitcoin Core](#building-bitcoin-core)
 - [Building an alternative repository](#building-an-alternative-repository)
 - [Signing externally](#signing-externally)
 - [Uploading signatures](#uploading-signatures)
@@ -95,11 +95,11 @@ After creating the VM, we need to configure it.
 
 - Click `Ok` twice to save.
 
-Get the [Debian 8.x net installer](http://cdimage.debian.org/debian-cd/8.4.0/amd64/iso-cd/debian-8.4.0-amd64-netinst.iso) (a more recent minor version should also work, see also [Debian Network installation](https://www.debian.org/CD/netinst/)).
+Get the [Debian 8.x net installer](http://cdimage.debian.org/debian-cd/8.5.0/amd64/iso-cd/debian-8.5.0-amd64-netinst.iso) (a more recent minor version should also work, see also [Debian Network installation](https://www.debian.org/CD/netinst/)).
 This DVD image can be validated using a SHA256 hashing tool, for example on
 Unixy OSes by entering the following in a terminal:
 
-    echo "7a6b418e6a4ee3ca75dda04d79ed96c9e2c33bb0c703ca7e40c6374ab4590748  debian-8.4.0-amd64-netinst.iso" | sha256sum -c
+    echo "ad4e8c27c561ad8248d5ebc1d36eb172f884057bfeb2c22ead823f59fa8c3dff  debian-8.5.0-amd64-netinst.iso" | sha256sum -c
     # (must return OK)
 
 Then start the VM. On the first launch you will be asked for a CD or DVD image. Choose the downloaded iso.
@@ -342,10 +342,10 @@ manual intervention. Also optionally follow the next step: 'Seed the Gitian sour
 and offline git repositories' which will fetch the remaining files required for building
 offline.
 
-Building Bitcoin
+Building Bitcoin Core
 ----------------
 
-To build Bitcoin (for Linux, OS X and Windows) just follow the steps under 'perform
+To build Bitcoin Core (for Linux, OS X and Windows) just follow the steps under 'perform
 Gitian builds' in [doc/release-process.md](release-process.md#perform-gitian-builds) in the bitcoin repository.
 
 This may take some time as it will build all the dependencies needed for each descriptor.