docs: add fetch install command for FreeBSD (#9172)

Co-authored-by: Marc Cornellà <marc.cornella@live.com>

README.md

@@ -43,6 +43,12 @@ sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/too
 sh -c "$(wget -O- https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
 ```
 
+#### via fetch
+
+```shell
+sh -c "$(fetch -o - https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
+```
+
 #### Manual inspection
 
 It's a good idea to inspect the install script from projects you don't yet know. You can do

tools/install.sh

@@ -2,8 +2,10 @@
 #
 # This script should be run via curl:
 #   sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
-# or wget:
+# or via wget:
 #   sh -c "$(wget -qO- https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
+# or via fetch:
+#   sh -c "$(fetch -o - https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
 #
 # As an alternative, you can first download the install script and run it afterwards:
 #   wget https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh