replaces single quotes with double quotes

single quotes don't work in cmd.exe, this is an issue when working from within
RStudio terminal on Windows because cmd.exe is default "shell" there

fixes #67

basics.html

@@ -425,16 +425,16 @@
 
             ```bash
             # configure your identity
-            git config --global user.name  'Jane Doe'
-            git config --global user.email 'jane.doe@idiv.de'
+            git config --global user.name  "Jane Doe"
+            git config --global user.email "jane.doe@idiv.de"
 
             # show colors
             git config --global color.ui auto
 
             # configure aliases
-            git config --global alias.unstage 'reset HEAD --'
+            git config --global alias.unstage "reset HEAD --"
             git config --global alias.lol \
-              'log --graph --decorate --oneline --all'
+              "log --graph --decorate --oneline --all"
 
             # show config
             git config --list [--global]
@@ -454,7 +454,7 @@
             git config --global core.editor notepad
 
             # Mac
-            git config --global core.editor 'open -Wne'
+            git config --global core.editor "open -Wne"
 
             # Linux GNOME / KDE
             git config --global core.editor gedit
@@ -611,7 +611,7 @@
             git commit [-v]
 
             # commits with a short message
-            git commit -m 'initial commit'
+            git commit -m "initial commit"
             ```
 
             notes:
@@ -902,7 +902,7 @@
             ```
 
             notes:
-            - `git branch --list 'topic/*'`
+            - `git branch --list "topic/*"`
             - decide with your team, write `CONTRIBUTING.md`
           </section>