Minor typo fixes (#1459)

Author: hola-soy-milk

exercises/concept/factory-sensors/.docs/instructions.md

@@ -23,7 +23,7 @@ checkHumidityLevel(100);
 
 ## 2. Detect overheating
 
-Elena is very pleased with your first assignment and ask you to deal with the monitoring of the machines' temperature.
+Elena is very pleased with your first assignment and asks you to deal with the monitoring of the machines' temperature.
 While chatting with a technician, Greg, you are told that if the temperature of a machine exceeds 500°C, the technicians start worrying about overheating.
 
 The machine is equipped with a sensor that measures its internal temperature.

exercises/concept/lasagna-master/lasagna-master.spec.js

@@ -50,7 +50,7 @@ describe('preparationTime', () => {
     expect(preparationTime(fewLayers, 3.5)).toBe(7);
   });
 
-  test('uses the default if no customer time was passed', () => {
+  test('uses the default if no custom time was passed', () => {
     const manyLayers = [
       'sauce',
       'noodles',