Update 20-prerequisites.mdx

Author: wjteo

docs/20-prerequisites.mdx

@@ -41,7 +41,7 @@ The PostgreSQL server can be accessed at localhost:5432 with a username of `post
 ### Option 4: Load an SQL file
 Choose this option if you just want a quick hands-on experience and you don't need to run actual migration.
 Download the file [library-schema.sql](https://github.com/mongodb-developer/relational-migrator-lab/blob/main/resource/library-schema.sql)
-and upload this file later on at the **create a project** step. However, you will not be able to perform an actual migration if you not have a source database. 
+and upload this file later on at the **create a project** step. However, you will not be able to perform an actual migration since you do not have a source database. 
 
 ## 2. MongoDB Database
 
@@ -80,4 +80,4 @@ You can connect with no username or password. Since this command does not use Do
 
 
 Now you will need to go to the [MongoDB Relational Migrator downloads page](https://www.mongodb.com/try/download/relational-migrator), select your OS, download and install it. Once installed, 
-run it and it will be running on a browser at http://127.0.0.1:8278/.
+run it and it will be running on a browser at http://127.0.0.1:8278/.