Update reference to follow tiny change in PackedRichPID deltaLL

Related to LHCb!1288 (merged)

• [2018-04-29 00:23] Validation started with lhcb-lcg-dev3#509
• [2018-04-29 00:23] Validation started with lhcb-head#1835
• [2018-04-29 00:23] Validation started with lhcb-tdr-test#135
• [2018-04-29 00:24] Validation started with lhcb-clang-test#936
• [2018-04-29 00:26] Validation started with lhcb-gaudi-head-py3#138
• [2018-04-29 00:28] Validation started with lhcb-lcg-dev4#509
• [2018-04-29 00:32] Validation started with lhcb-gaudi-head#1851
• [2018-04-29 08:31] Validation started with lhcb-gaudi-merge#502
• [2018-04-29 12:18] Validation started with lhcb-head#1836
• [2018-04-30 00:22] Validation started with lhcb-lcg-dev3#510
• [2018-04-30 00:22] Validation started with lhcb-lcg-dev4#510
• [2018-04-30 00:25] Validation started with lhcb-tdr-test#136
• [2018-04-30 00:25] Validation started with lhcb-clang-test#937
• [2018-04-30 00:26] Validation started with lhcb-gaudi-head#1852
• [2018-04-30 00:29] Validation started with lhcb-gaudi-head-py3#139
• [2018-04-30 00:31] Validation started with lhcb-head#1837

changed title from Update reference to follow fix to PackedRichPID version, MR LHCb!1251 to Update reference to follow tiny change in PackedRichPID deltaLL

changed the description

mentioned in commit 3fcffc72

merged

changed the description