Removing unwanted quotes for code block in readme (#1808)

I just noticed leftover quotes from markdown that mess with the RST rendering

README.rst

@@ -57,19 +57,17 @@ environment (this is optional).
 The following command will set up a conda virtual environment, add the
 necessary package channels, and install ctapipe specified version and its dependencies::
 
-```
-CTAPIPE_VER=0.11.0
-wget https://raw.githubusercontent.com/cta-observatory/ctapipe/v$CTAPIPE_VER/environment.yml
-conda env create -n cta -f environment.yml
-conda activate cta
-conda install -c conda-forge ctapipe=$CTAPIPE_VER
-```
-
-**Note**: To prevent packages you installed with `pip install --user` from taking precedence over the conda environment, run:
-
-```
-conda env config vars set PYTHONNOUSERSITE=1 -n cta
-```
+    CTAPIPE_VER=0.11.0
+    wget https://raw.githubusercontent.com/cta-observatory/ctapipe/v$CTAPIPE_VER/environment.yml
+    conda env create -n cta -f environment.yml
+    conda activate cta
+    conda install -c conda-forge ctapipe=$CTAPIPE_VER
+
+
+**Note**: To prevent packages you installed with `pip install --user` from taking precedence over the conda environment, run::
+
+    conda env config vars set PYTHONNOUSERSITE=1 -n cta
+
   
 **Note**: this environment contains many useful packages that are not strictly requirements of ctapipe.
 To get only ctapipe and its direct dependencies, just do ``conda install -c conda-forge ctapipe[=<version>]`` in an environment