GEMS16 — Clarify the Standard ASCII Header

Change the description of Table 8.2 from "Standard Request Message Fields" to "Standard header" since it is the ASCII standard header as referenced throughout section 8.

Change the reference "<See Table 9.2>" to "<See Table 8.2>" in the first row of Table 8.3 for Standard Header to match all other references. Table 9.2 does not exist.