Enhance features & functions for vnstock v 1.0.6

[thinh-vu]

• Revised and categorized the usage of features and functions into 5 main pillars:
  1. Market Watch
  2. Fundamental Analysis
  3. Technical Analysis
  4. Stock Pick
  5. Trading Center
• Improved the structure and usability of existing functions.
• Added new functions to support enhanced capabilities in Fundamental Analysis and Stock Pick.