Doc changes in Jstack, Jmap and similar tools

Before JDK 9, both SA and Attach api based J* tools could be launched from the same command. That is, <jdk>/bin/jstack could be used for both attaching to process and core file.

JDK 9 and above, SA tools have been moved under a common launcher called Jhsdb. So now, you can attach to a process with either the attach api based tools or SA based tools. You can attach to core file with SA based tools. But I think, this difference has not been brought out in the documentation (needs more verification). We need to mention this and also talk about the difference between these tools w.r.t the user.

The documentation wrongly suggests that <jdk>/bin/jstack can still be used with core file (https://docs.oracle.com/javase/10/troubleshoot/diagnostic-tools.htm#JSTGD213). This needs to be corrected for all such tools.

I will use this as an umbrella task and open further doc bugs for these items.