Update Developer Guide to include Find Exercises feature

Add sequence diagram for Find Exercises using PlantUML

docs/DeveloperGuide.md

@@ -217,6 +217,20 @@ _{more aspects and alternatives to be added}_
 
 _{Explain here how the data archiving feature will be implemented}_
 
+### Find exercises 
+
+The find exercises feature is implemented using `FindExercisesCommandParser`, as well as the following command:
+* `FindExercisesCommand`, to be executed when the user inputs the command into fitNUS
+
+`FindExercisesCommandParser` takes in the user input and parses them to return a FindExercisesCommand containing the 
+corresponding predicate for finding the exercises. When executed, `FindExercisesCommand` will set the predicate of 
+the respective `FilteredList` for exercises in `ModelManager` such that only exercises matching the predicate will be 
+displayed in the list.
+
+Given below is the Sequence Diagram for interactions within the Logic component for the execute("find_exercises bench") 
+API call.
+![FindExercisesSequenceDiagram](images/FindExercisesSequenceDiagram.png)
+
 
 --------------------------------------------------------------------------------------------------------------------
 

docs/diagrams/FindExercisesSequenceDiagram.puml

@@ -0,0 +1,69 @@
+@startuml
+!include style.puml
+
+box Logic LOGIC_COLOR_T1
+participant ":LogicManager" as LogicManager LOGIC_COLOR
+participant ":AddressBookParser" as AddressBookParser LOGIC_COLOR
+participant ":FindExercisesCommandParser" as FindExercisesCommandParser LOGIC_COLOR
+participant "f:FindExercisesCommand" as FindExercisesCommand LOGIC_COLOR
+participant ":CommandResult" as CommandResult LOGIC_COLOR
+end box
+
+box Model MODEL_COLOR_T1
+participant ":Model" as Model MODEL_COLOR
+end box
+
+[-> LogicManager : execute("find_exercises bench")
+activate LogicManager
+
+LogicManager -> AddressBookParser : parseCommand("find_exercises bench")
+activate AddressBookParser
+
+create FindExercisesCommandParser
+AddressBookParser -> FindExercisesCommandParser
+activate FindExercisesCommandParser
+
+FindExercisesCommandParser --> AddressBookParser
+deactivate FindExercisesCommandParser
+
+AddressBookParser -> FindExercisesCommandParser : parse("bench")
+activate FindExercisesCommandParser
+
+create FindExercisesCommand
+FindExercisesCommandParser -> FindExercisesCommand
+activate FindExercisesCommand
+
+FindExercisesCommand --> FindExercisesCommandParser : f
+deactivate FindExercisesCommand
+
+FindExercisesCommandParser --> AddressBookParser : f
+deactivate FindExercisesCommandParser
+'Hidden arrow to position the destroy marker below the end of the activation bar.
+FindExercisesCommandParser -[hidden]-> AddressBookParser
+destroy FindExercisesCommandParser
+
+AddressBookParser --> LogicManager : f
+deactivate AddressBookParser
+
+LogicManager -> FindExercisesCommand : execute()
+activate FindExercisesCommand
+
+FindExercisesCommand-> Model : updateFilteredExerciseList(predicate)
+activate Model
+
+Model --> FindExercisesCommand
+deactivate Model
+
+create CommandResult
+FindExercisesCommand -> CommandResult
+activate CommandResult
+
+CommandResult --> FindExercisesCommand
+deactivate CommandResult
+
+FindExercisesCommand --> LogicManager : result
+deactivate FindExercisesCommand
+
+[<--LogicManager
+deactivate LogicManager
+@enduml