Add technical analysis document on RV-BIS independence in Bayesian joint modeling

- Introduced a comprehensive markdown document detailing the analysis of information redundancy between Radial Velocity (RV) and Bisector Inverse Slope (BIS) in the context of Bayesian joint modeling, referencing Rajpaul et al. (2015).
- Included mathematical formulations, empirical validations, and diagnostic criteria for assessing the independence of RV and BIS measurements.