docs: Update docs to reflect content spec v1.4.0 (#483)

Because we have made changes to the content specification

this commit will:
- update the documentation to describe the new spec version

**Certification**
- [X] I certify that <!-- Check the box to certify: [X] -->
- I have read the [contributing guidelines](
  https://github.com/nodepa/seedlingo/blob/main/.github/CONTRIBUTING.md)
- I license these contributions to the public under Seedlingo's
  [LICENSE](https://github.com/nodepa/seedlingo/blob/main/LICENSE.md)
  and have the rights to do so.

Signed-off-by: toshify <4579559+toshify@users.noreply.github.com>

docs/architecture/architecture.md

@@ -43,9 +43,10 @@ e.g. /unit/4 directs links of that pattern to src/views/ExerciseSession.vue
 ## src/views/ExerciseSession.vue
 
 `ExerciseSession` presents one of the exercise components
-MatchingExercise.vue, MultipleChoiceExercise.vue or ClozeExercise.vue
-based on the `exercise`/`exerciseItems` generated
-by src/Units/ExerciseProvider.ts.
+MatchingExercise.vue, MultipleChoiceExercise.vue,
+ClozeExercise.vue or ComprehensionExercise.vue
+based on the `exercise`/`exerciseItems` generated by
+src/Units/ExerciseProvider.ts.
 When `ExerciseSession` is made available in the page/mounted,
 `getExercise()` is used to identify the correct unit
 specified by the `/unit/:id` route param in the browser's address bar.
@@ -61,7 +62,7 @@ then generates an exercise of random type from the unit
 using `GenerateExerciseOfType[ExerciseType].bind(this)(unit)`
 (where ExerciseType is randomly picked from types available in the unit),
 which executes the relevant
-`generate[Matching|MultipleChoice|ExplanationMatching|ExplanationMultipleChoice|SingleCloze|MultiCloze]Exercise(unit)`.
+`generate[Matching|MultipleChoice|ExplanationMatching|ExplanationMultipleChoice|SingleCloze|MultiCloze|Comprehension]Exercise(unit)`.
 I.e. for `generateMultipleChoiceExercise`,
 a random exercise specification from the unit is selected,
 then 4 random word references from that exercise are selected,