docs: 🔥 remove get_potential_pcos() and get_wld_purchases() (#144)

## Description 

As discussed earlier today: Since these functions were supposed to do
some very simple filtering, we actually don't need them after all.

This PR also regenerates the pumls as SVGs instead of PNGs and updates
the `justfile` recipe for generating pumls.

justfile

@@ -1,10 +1,10 @@
 @_default:
     just --list --unsorted
 
-# Generate PNG images from all PlantUML files
+# Generate svg images from all PlantUML files
 generate-puml-all:
-  docker run --rm -v $(pwd):/puml -w /puml ghcr.io/plantuml/plantuml:1.2024.3 -tpng "**/*.puml"
+  docker run --rm -v $(pwd):/puml -w /puml ghcr.io/plantuml/plantuml:1.2024.3 -tsvg "**/*.puml"
 
-# Generate PNG image from specific PlantUML file
+# Generate svg image from specific PlantUML file
 generate-puml name:
-  docker run --rm -v  $(pwd):/puml -w /puml ghcr.io/plantuml/plantuml:1.2024.3 -tpng "**/{{name}}.puml"
+  docker run --rm -v  $(pwd):/puml -w /puml ghcr.io/plantuml/plantuml:1.2024.3 -tsvg "**/{{name}}.puml"

vignettes/images/function-flow-population.puml

@@ -32,9 +32,6 @@ hide <<exclusion>> stereotype
             action "join_lpr3()" as lpr3
     }
 
-    action "get_potential_pcos()" as pcos
-    action "get_wld_purchases()" as wld
-
     together {
         action "exclude_pregnancy()" as ex_pregnancy <<exclusion>>
         action "exclude_wld_purchases()" as ex_wld <<exclusion>>
@@ -77,15 +74,13 @@ hide <<exclusion>> stereotype
     lpr2 --> in_diagnoses
     lpr3 --> in_diagnoses
     in_diagnoses --> join_inclusion
-
-'helper functions
+
+'exclusion and helper functions
+    bef --> ex_pcos
+    lmdb --> ex_wld
     lpr2 --> pregnancy
     lpr3 --> pregnancy
     pregnancy --> ex_pregnancy
-    lmdb --> wld
-    wld --> ex_wld
-    bef --> pcos
-    pcos --> ex_pcos
     join_inclusion --> diagnosis_date
 
 @enduml