Add Linux/Ubuntu ssl-check shell function instructions

docs/v1/versioned_docs/version-1.0.0-beta.14/Create-a-self-signed-SSL-certificate.md

@@ -14,6 +14,7 @@ brew install mkcert
 
 2. Copy and paste the bash function into your terminal (or into your `.bashrc` file if you want to have it available in the future):
 
+### Mac
 ```bash
 function ssl-check() {
     f=~/.localhost_ssl;
@@ -62,6 +63,56 @@ function ssl-check() {
 }
 ```
 
+### Linux/Ubuntu
+```bash
+function ssl-check() {
+         f=~/.localhost_ssl;
+         ssl_crt=$f/server.crt
+         ssl_key=$f/server.key
+         b=$(tput bold)
+         c=$(tput sgr0)
+
+         # gets all IPs returned by the hostname function
+         ips=$(hostname -I)
+         local_ips=($(echo $ips | tr " " "\n"))
+         # local_ip=999.999.999 # (uncomment for testing)
+
+         domains=(
+             "localhost"
+             "${local_ips[@]}"
+         )
+
+         if [[ ! -f $ssl_crt ]]; then
+             echo -e "\n🛑  ${b}Couldn't find a Slate SSL certificate:${c}"
+             make_key=true
+         elif [[ ! $(openssl x509 -noout -text -in $ssl_crt | grep $local_ip) ]]; then
+             echo -e "\n🛑  ${b}Your IP Address has changed:${c}"
+             make_key=true
+         else
+             echo -e "\n✅  ${b}Your IP address is still the same.${c}"
+         fi
+
+         if [[ $make_key == true ]]; then
+             echo -e "Generating a new Slate SSL certificate...\n"
+             count=$(( ${#domains[@]} - 1))
+             mkcert ${domains[@]}
+
+             # Create Slate's default certificate directory, if it doesn't exist
+             test ! -d $f && mkdir $f
+
+             # It appears mkcert bases its filenames off the number of domains passed after the first one.
+             # This script predicts that filename, so it can copy it to Slate's default location.
+             if [[ $count = 0 ]]; then
+                 mv ./localhost.pem $ssl_crt
+                 mv ./localhost-key.pem $ssl_key
+             else
+                 mv ./localhost+$count.pem $ssl_crt
+                 mv ./localhost+$count-key.pem $ssl_key
+             fi
+         fi
+     }
+```
+
 3. Run the function you just declared in step 2:
 
 ```bash