Add wilders_rsi indicator

Author: MDUYN

README.md

@@ -19,6 +19,7 @@ pip install pyindicators
   * [Exponential Moving Average (EMA)](#exponential-moving-average-ema)
 * Momentum indicators
   * [Relative Strength Index (RSI)](#relative-strength-index-rsi)
+  * [Relative Strength Index Wilders method (RSI)](#relative-strength-index-rsi)
 
 ## Indicators
 
@@ -99,7 +100,32 @@ pd_df = ema(pd_df, source_column="Close", period=200, result_column="RSI_14")
 pd_df.tail(10)
 ```
 
-![EMA](https://github.com/coding-kitties/PyIndicators/blob/main/static/images/indicators/rsi.png)
+![RSI](https://github.com/coding-kitties/PyIndicators/blob/main/static/images/indicators/rsi.png)
+
+#### Wilders Relative Strength Index (Wilders RSI)
+
+```python
+from investing_algorithm_framework import CSVOHLCVMarketDataSource
+
+from pyindicators import wilders_rsi
+
+# For this example the investing algorithm framework is used for dataframe creation,
+csv_path = "./tests/test_data/OHLCV_BTC-EUR_BINANCE_15m_2023-12-01:00:00_2023-12-25:00:00.csv"
+data_source = CSVOHLCVMarketDataSource(csv_file_path=csv_path)
+
+pl_df = data_source.get_data()
+pd_df = data_source.get_data(pandas=True)
+
+# Calculate SMA for Polars DataFrame
+pl_df = wilders_rsi(pl_df, source_column="Close", period=200, result_column="RSI_14")
+pl_df.show(10)
+
+# Calculate SMA for Pandas DataFrame
+pd_df = wilders_rsi(pd_df, source_column="Close", period=200, result_column="RSI_14")
+pd_df.tail(10)
+```
+
+![RSI](https://github.com/coding-kitties/PyIndicators/blob/main/static/images/indicators/wilders_rsi.png)
 
 ### Indicator helpers