Add "Help" link on the "System Info" page

Support often gets customers who due limited understanding of JAVA and JVM getting highly concern about the memory utilisation in JIRA.

The stats are perceived as an indicator of a performance problem with JIRA. Below I've listed common is misconceptions about behaviour JVM and garbage collection:

• JIRA always uses 100% mem,
• I have to 'Force garbage collection' in order to release memory,
• JIRA feels slow and i noticed it uses all memory

By creating a doco page and link it to the product, we could help our users to understand the provided stats in a better way.