Fixed RC tag (#4387) (#4388)

#       A Public Release for ISIS3.6.1:                        {% set version = "3.6.1" %}

#       A Release Candidate for ISIS3.6.1:                     {% set version = "3.6.1_RC" %}

#       A custom build of ISIS3.6.1 for the CaSSIS mission:    {% set version = "3.6.1_cassis" %}

{% set version = "5.0.0_RC" %}

{% set version = "5.0.0_RC1" %}

# This is the build number for the current version you are building. If this is the first build of

# this version, the build number will be 0. It is incremented by 1 with every consecutive build of