Update README to reflect handling IP conflict by using LATTICE_SYSTEM_IP variable.
Update README to reflect handling IP conflict by using LATTICE_SYSTEM_IP variable.

[Finishes #85279384]

Signed-off-by: David Wadden <ff4ebafbe4a7d77cde45f9afefafd7a5dfa94f36@pivotal.io>

mikegehard/lattice,svrc-pivotal/lattice,Klaudit/lattice,datachand/lattice,davidwadden/lattice,Klaudit/lattice,felipeg48/lattice,davidwadden/lattice,cloudfoundry-incubator/ltc,SrinivasChilveri/lattice,Klaudit/lattice,datachand/lattice,svrc-pivotal/lattice,datachand/lattice,SrinivasChilveri/lattice,davidwadden/lattice-release,svrc-pivotal/lattice,cloudfoundry-incubator/ltc,svrc-pivotal/lattice,datachand/lattice,Klaudit/lattice,mikegehard/lattice,SrinivasChilveri/lattice,davidwadden/lattice-release,felipeg48/lattice,SrinivasChilveri/lattice