fix typo

Author: jrcunning

_episodes/05-writing-scripts.md

@@ -15,7 +15,7 @@ keypoints:
 
 ## Writing files
 
-We've been able to do a lot of work with files that already exist, but what if we want to write our own files. We're not going to type in a FASTA file, but we'll see as we go through other tutorials, there area lot of reasons we'll want to write a file, or edit an existing file.
+We've been able to do a lot of work with files that already exist, but what if we want to write our own files. We're not going to type in a FASTA file, but we'll see as we go through other tutorials, there are a lot of reasons we'll want to write a file, or edit an existing file.
 
 To add text to files, we're going to use a text editor called Nano. We're going to create a file to take notes about what we've been doing with the data files in `~/dc_sample_data/untrimmed_fastq`.