updated git installation macOS/Linux

modules/setup_unix/environment_installation.md

@@ -215,24 +215,36 @@ Git should be installed on your computer as part of your Bash install
 
 #### macOS
 
-<strong>For macOS/Mac OS X 10.9 and higher</strong>, install Git for
-Mac by downloading and running the most recent "mavericks" installer
-from <a
+Recent versions of macOS should have `git` already
+installed (or you had it installed together with
+[Xcode](https://developer.apple.com/xcode/)). 
+Check on the command line by running the command
+```bash
+git version
+```
+If this gives an output such as *git version 2.41.0* then you have `git`.
+
+For older macOS/Mac OS X 10.9 and higher, install Git for Mac by
+downloading and running the most recent "mavericks" installer from <a
 href="https://sourceforge.net/projects/git-osx-installer/files/">this
-list</a>.  After installing Git, there will not be anything in your
-<code>/Applications</code> folder, as Git is a command line program.
+list</a>.  Because this installer is not signed by the developer, you
+may have to right click (control click) on the .pkg file, click Open,
+and click Open on the pop up window. After installing Git, there will
+not be anything in your <code>/Applications</code> folder, as Git is a
+command line program.
+
 
 
 #### Linux
 
 If Git is not already available on your machine you can try to install
 it via your distro's package manager. For *Debian/Ubuntu* run 
 ```bash
-sudo apt-get install git
+sudo apt-get install git-all
 ```
 and for *Fedora* run 
 ```bash
-sudo yum install git
+sudo dnf install git-all
 ```
 
 #### ChromeOS ####