#8 update histogram example

sphinx/source/examples/histogram/README.txt

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+***********
+Histogram Charts
+***********
+
+Below is a gallery of histogram chart. 
+
+- RICK Histogram Chart: plot a histogram chart using a customized normal distribution

sphinx/source/examples/histogram/plot_histogram.py

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+"""
+RICK Histogram Chart
+=======================
+
+Example of a histogram chart.
+"""
+import os
+import os.path as osp
+import sys
+sys.path.append(osp.dirname(osp.dirname(osp.dirname(osp.dirname(osp.dirname(osp.abspath(__file__)))))))
+
+from sqlalchemy import create_engine
+import matplotlib.pyplot as plt
+import matplotlib as mpl
+import pandas as pd 
+import configparser
+from psycopg2 import connect
+import psycopg2.sql as pg
+import pandas.io.sql as pandasql
+import numpy as np 
+import datetime
+import math
+import rick
+import geopandas as gpd
+import os
+import shapely
+from shapely.geometry import Point
+####os.environ["PROJ_LIB"]=r"C:\Users\rliu4\AppData\Local\Continuum\anaconda3\Library\share"
+import importlib
+import matplotlib.ticker as ticker
+import matplotlib.font_manager as font_manager
+import numpy as np
+
+################################
+#histogram_chart
+#--------------------------
+#
+#This Section uses the histogram_chart function with a customized dataframe.
+
+rng = np.random.default_rng()
+numbers = rng.normal(size=10_000)
+
+##plt.hist(numbers)
+fig, ax = rick.charts.histogram_chart(numbers, ylab = 'hist', xlab = '', xmin=-3, nbin=100)
+fig.tight_layout()
+plt.show()