chore(translation): add certsign jks to en-GB

src/main/resources/messages_en_GB.properties

@@ -546,9 +546,11 @@ scalePages.submit=Submit
 certSign.title=Certificate Signing
 certSign.header=Sign a PDF with your certificate (Work in progress)
 certSign.selectPDF=Select a PDF File for Signing: 
+certSign.jksNote=Note: If your certificate type is not listed below, please convert it to a Java Keystore (.jks) file using the keytool command line tool. Then, choose the .jks file option below.
 certSign.selectKey=Select Your Private Key File (PKCS#8 format, could be .pem or .der): 
 certSign.selectCert=Select Your Certificate File (X.509 format, could be .pem or .der): 
 certSign.selectP12=Select Your PKCS#12 Keystore File (.p12 or .pfx) (Optional, If provided, it should contain your private key and certificate): 
+certSign.selectJKS=Select Your Java Keystore File (.jks or .keystore):
 certSign.certType=Certificate Type
 certSign.password=Enter Your Keystore or Private Key Password (If Any): 
 certSign.showSig=Show Signature