fix(curriculum): change projects hint article links (#42339)

What?
Make "Get a Hint" links of some projects to point to their
corresponding forum topics.
Ref: https://github.com/freeCodeCamp/freeCodeCamp/issues/40472#issuecomment-850496017

How?
Set `forumTopicId` in the front matter of the project files.

Closes #40472

curriculum/challenges/english/11-machine-learning-with-python/machine-learning-with-python-projects/book-recommendation-engine-using-knn.md

@@ -2,6 +2,7 @@
 id: 5e46f8e3ac417301a38fb92f
 title: Book Recommendation Engine using KNN
 challengeType: 10
+forumTopicId: 462378
 dashedName: book-recommendation-engine-using-knn
 ---
 

curriculum/challenges/english/11-machine-learning-with-python/machine-learning-with-python-projects/cat-and-dog-image-classifier.md

@@ -2,6 +2,7 @@
 id: 5e46f8dcac417301a38fb92e
 title: Cat and Dog Image Classifier
 challengeType: 10
+forumTopicId: 462377
 dashedName: cat-and-dog-image-classifier
 ---
 

curriculum/challenges/english/11-machine-learning-with-python/machine-learning-with-python-projects/linear-regression-health-costs-calculator.md

@@ -2,6 +2,7 @@
 id: 5e46f8edac417301a38fb930
 title: Linear Regression Health Costs Calculator
 challengeType: 10
+forumTopicId: 462379
 dashedName: linear-regression-health-costs-calculator
 ---
 

curriculum/challenges/english/11-machine-learning-with-python/machine-learning-with-python-projects/neural-network-sms-text-classifier.md

@@ -2,6 +2,7 @@
 id: 5e46f8edac417301a38fb931
 title: Neural Network SMS Text Classifier
 challengeType: 10
+forumTopicId: 462380
 dashedName: neural-network-sms-text-classifier
 ---
 

curriculum/challenges/english/11-machine-learning-with-python/machine-learning-with-python-projects/rock-paper-scissors.md

@@ -2,6 +2,7 @@
 id: 5e46f8d6ac417301a38fb92d
 title: Rock Paper Scissors
 challengeType: 10
+forumTopicId: 462376
 dashedName: rock-paper-scissors
 ---