[UG] Fix a typo in GRAPH_TYPE param description
[UG] Fix a typo in GRAPH_TYPE param description

This patch replaces the duplicated GRAPH_TYPES param with
a more explicit description of the command and the
param itself.

Closes-Bug: #1649854

Change-Id: Ib025a5dd0fd7f51b832ab7409ef6b5daca8e61d2

stackforge/fuel-docs,stackforge/fuel-docs