updating DIRECTORY.md

Author: cclauss

DIRECTORY.md

@@ -169,7 +169,7 @@
   * [Prefix Conversions](conversions/prefix_conversions.py)
   * [Prefix Conversions String](conversions/prefix_conversions_string.py)
   * [Pressure Conversions](conversions/pressure_conversions.py)
-  * [Rec To Pol](conversions/rec_to_pol.py)
+  * [Rectangular To Polar](conversions/rectangular_to_polar.py)
   * [Rgb Cmyk Conversion](conversions/rgb_cmyk_conversion.py)
   * [Rgb Hsv Conversion](conversions/rgb_hsv_conversion.py)
   * [Roman Numerals](conversions/roman_numerals.py)