Update usage_guide.md links

Author: Tara Raj

doc/usage_guide.md

@@ -1,18 +1,18 @@
 # Usage Guide
 Contents:
 
-[Options](#Options)
+[Options](#options)
 
-[Examples](#Examples)
+[Examples](#examples)
 
-[Environment Variables](#Environment-Variables)
+[Environment Variables](#environment-variables)
 
 ## Description
 mssql-scripter is the multiplatform command line equivalent of the widely used Generate Scripts Wizard experience in SSMS.
 
 You can use mssql-scripter on Linux, macOS, and Windows to generate data definition language (DDL) and data manipulation language (DML) T-SQL scripts for database objects in SQL Server running anywhere, Azure SQL Database, and Azure SQL Data Warehouse. You can save the generated T-SQL script to a .sql file or pipe it to standard *nix utilities (for example, sed, awk, grep) for further transformations. You can edit the generated script or check it into source control and subsequently execute the script in your existing SQL database deployment processes and DevOps pipelines with standard multiplatform SQL command line tools such as sqlcmd.
 
-  ## Options
+## Options
 For option parameters, pass in '-h': 
 
     $ mssql-scripter -h
@@ -145,7 +145,7 @@ Below are example commands that run against the AdventureWorks database. Here is
 
 [Dump datbase object data](#dump-database-object-data)
 
-[Dump datbase object schema and data](#dump-database-object-schema-and-data)
+[Dump database object schema and data](#dump-the-database-object-schema-and-data)
 
 [Include database objects](#include-database-objects)