Suggestion: Add optimization functions, ml algorithms under `machine_learning` folder

I would like to suggest adding Optimization functions, machine learning and deep learning algorithms in this repository. This can be added in a separate folder called machine_learning folder. Further, this folder can contain various algorithms that are used in machine learning and deep learning.

Initially, these Optimization functions can be added under machine_learning/optimization/

• Gradient Descent
• Stochastic Gradient Descent (SGD)
• Mini-Batch Gradient Descent
• Adam (Adaptive Moment Estimation)
• RMSprop (Root Mean Square Propagation)
• AdaGrad (Adaptive Gradient Algorithm)

And these in machine_learning/

• Linear Regression
• Logistic Regression
• Decision Trees
• Random Forest
• Support Vector Machines (SVM)
• K-Nearest Neighbors (K-NN)
• Naive Bayes
• K-Means Clustering
• Principal Component Analysis (PCA)

Start by reviewing the existing machine_learning/optimization/ and machine_learning/ entries, including the listed Gradient Descent and Linear Regression work. Narrow the broad proposal to one unimplemented algorithm, such as SGD or Logistic Regression, before deciding the exact scope. Done should mean that one clearly selected algorithm is added in the appropriate folder and its checklist item is completed.