EulerGuide: add a note about singularity

Author: emanuel-schmid

doc/guide/Guide_Euler.ipynb

@@ -26,7 +26,7 @@
    },
    "source": [
     "\n",
-    "## Installation and working directories\n",
+    "## Installation direectory and working directory\n",
     "\n",
     "Please, get familiar with the various Euler storage options:  https://scicomp.ethz.ch/wiki/Storage_systems.<br>\n",
     "As a general rule: use `/cluster/project` for installation and `/cluster/work` for data processing.\n",
@@ -45,7 +45,7 @@
    "metadata": {},
    "source": [
     "\n",
-    "## Climada installation in virtual environment\n",
+    "## Climada installation in a virtual environment\n",
     "\n",
     "Climada is pre-installed and available in the default pip environment of Euler."
    ]
@@ -196,7 +196,7 @@
    "metadata": {},
    "source": [
     "\n",
-    "## Run Jupyter Notebook on Euler"
+    "## Run a Jupyter Notebook on Euler"
    ]
   },
   {
@@ -280,7 +280,10 @@
    "source": [
     "## Fall back: Singularity Container\n",
     "\n",
-    "To install climada into a singularity container, follow these steps:"
+    "In case the installation in a virtual environment does not work, e.g,, because some module on Euler in incompatible with additional requirements for Python packages, the last resort is an installation of CLIMADA into a Singularity container. \\\n",
+    "In general, this is more difficult and time-consuming and easier to get wrong. It also requires a lot of diskspace and produces a high number of files, but it provides more flexibility, as one can install basically anything you want.\n",
+    "\n",
+    "To install CLIMADA into a Singularity container, follow these steps:"
    ]
   },
   {