Update README.md to newest spack version (#908)

* Update README.md to newest spack version

* Use correct version for link

* Update to newest spack version

* Use correct spack version

README.md

@@ -7,6 +7,7 @@ Spack is the package manager used by C2SM and MeteoSwiss to install and deploy s
 
 **Infos about c2sm-supported software and machines**
   * [spack-c2sm latest](https://C2SM.github.io/spack-c2sm/latest)
+  * [spack-c2sm v0.20.1.4](https://C2SM.github.io/spack-c2sm/v0.20.1.4)
   * [spack-c2sm v0.20.1.3](https://C2SM.github.io/spack-c2sm/v0.20.1.3)
   * [spack-c2sm v0.20.1.0](https://C2SM.github.io/spack-c2sm/v0.20.1.0)
   * [spack-c2sm v0.18.1.12](https://C2SM.github.io/spack-c2sm/v0.18.1.12)
@@ -31,7 +32,7 @@ With spack v0.18 we suggest local/individual spack instances and the use of spac
 
 A user clones the spack repo
 ```bash
-git clone --depth 1 --recurse-submodules --shallow-submodules -b v0.20.1.3 https://github.com/C2SM/spack-c2sm.git
+git clone --depth 1 --recurse-submodules --shallow-submodules -b v0.20.1.5 https://github.com/C2SM/spack-c2sm.git
 ```
 gets spack in the command line
 ```bash

docs/QuickStart.rst

@@ -5,7 +5,7 @@ Quick Start
 At CSCS (Daint, Tsa, Balfrin)
 -----------------------------
 
-To set up a Spack instance, clone the repository using a specific Spack tag (latest ``SPACK_TAG=v0.20.1.0``).
+To set up a Spack instance, clone the repository using a specific Spack tag (latest ``SPACK_TAG=v0.20.1.5``).
 
 .. code-block:: console
 
@@ -129,7 +129,7 @@ Out-of-source builds are possible as follows:
 
     $ mkdir cpu && cd cpu
     $ cp -r ../config .
-    $ spack env activate -d config/cscs/spack/v0.20.1.0/daint_cpu_nvhpc
+    $ spack env activate -d config/cscs/spack/v0.20.1.5/daint_cpu_nvhpc
     $ spack install
 
 ..  attention::