[Issue #195][SD] added UML sequence diagram for synonym retrieval C4.S02
[Issue #195][SD] added UML sequence diagram for C4.S12 and updated that of C4.S02
[Issue #195][Updating] resolved a typo in keyword.rb retrieve_synonyms method
Merge branch 'word_management_theme' of https://github.com/MGhanem/smartsoft-13 into C4_NourhanMohamed_S12_advanced_search