Update execution instructions

README.md

@@ -1,2 +1,30 @@
 # epm
 Baby name chooser
+
+# Usage
+```
+python3 src/elige_por_mi.py
+usage: elige_por_mi.py [-h] -a LISTA_1 -b LISTA_2 [-r RANKING_FILE]
+elige_por_mi.py: error: the following arguments are required: -a/--list1, -b/--list2
+```
+
+```
+python3 src/elige_por_mi.py -h
+usage: elige_por_mi.py [-h] -a LISTA_1 -b LISTA_2 [-r RANKING_FILE]
+
+Elijo nombre por ti si me das un par de listas.
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -a LISTA_1, --list1 LISTA_1
+                        lista de 6 nombres
+  -b LISTA_2, --list2 LISTA_2
+                        lista de 6 nombres
+  -r RANKING_FILE, --ranking RANKING_FILE
+                        ranking de nombres más usados
+```
+
+# Example:
+```
+python3 src/elige_por_mi.py -a data/lista_1.txt -b data/lista_2.txt
+```