Fix typo in CustomizingAzdParameters.md (#772)

Author: Thanusree-Microsoft

docs/CustomizingAzdParameters.md

@@ -3,7 +3,7 @@
 By default this template will use the environment name as the prefix to prevent naming collisions within Azure. The parameters below show the default values. You only need to run the statements below if you need to change the values. 
 
 
-> To override any of the parameters, run `azd env set <PARAMETER_NAME> <VALUE>` before running `azd up`. On the first azd command, it will prompt you for the environment name. Be sure to choose 3-20 charaters alphanumeric unique name. 
+> To override any of the parameters, run `azd env set <PARAMETER_NAME> <VALUE>` before running `azd up`. On the first azd command, it will prompt you for the environment name. Be sure to choose 3-20 characters alphanumeric unique name. 
 
 ## Parameters