tooldoc change for JDK-8057810

Update keytool and jarsigner tooldocs as described in http://ccc.us.oracle.com/8057810.

Note 1: Apply the same wording style of jarsigner - 1 - 2nd part (i.e. "private key is of DSA type") to RSA and EC also. Remove "attempts" for RSA.

Note 2: As for warning in jarsigner - 3, use the same text in keytool.html but remove mentioning of -keysize.