Fix tense in configuration.md

Amanda Butler · web-flow · commit 429af74e87b3 · 2018-11-28T18:18:14.000-06:00
Make edits for minor grammar nits.
diff --git a/docs/reference/configuration/configuration.md b/docs/reference/configuration/configuration.md
@@ -164,7 +164,7 @@ For example:
 }
 ```
 
-You define a configuration parameter by specifying its name as the key and specifying its value either with a description object or by value. Leaving the value field undefined or setting the value field to `null` will allow the parameter to be stored as a configuration option and appear with the `mbed compile --config` command; however, the key will not be defined in `mbed_config.h` and will not affect the application or OS unless it is overridden. See `param2` and `param5` for examples of this. The JSON fragment above defines six configuration parameters named `param1`, `param2`, `param3`, `param4`, `param5` and `param6`.
+You define a configuration parameter by specifying its name as the key and specifying its value either with a description object or by value. Leaving the value field undefined or setting the value field to `null` allows the parameter to be stored as a configuration option and appear with the `mbed compile --config` command; however, the key is not be defined in `mbed_config.h` and does not affect the application or OS unless it is overridden. See `param2` and `param5` for examples of this. The JSON fragment above defines six configuration parameters named `param1`, `param2`, `param3`, `param4`, `param5` and `param6`.
 
 Above, the configuration parameters `param1` through `param5` are defined using a description object. The description object supports the following keys:
 

Original file line number	Diff line number	Diff line change
`@@ -164,7 +164,7 @@ For example:`
`164`	`164`	`}`
`165`	`165`	```
`166`	`166`
`167`		-You define a configuration parameter by specifying its name as the key and specifying its value either with a description object or by value. Leaving the value field undefined or setting the value field to `null` will allow the parameter to be stored as a configuration option and appear with the `mbed compile --config` command; however, the key will not be defined in `mbed_config.h` and will not affect the application or OS unless it is overridden. See `param2` and `param5` for examples of this. The JSON fragment above defines six configuration parameters named `param1`, `param2`, `param3`, `param4`, `param5` and `param6`.
	`167`	+You define a configuration parameter by specifying its name as the key and specifying its value either with a description object or by value. Leaving the value field undefined or setting the value field to `null` allows the parameter to be stored as a configuration option and appear with the `mbed compile --config` command; however, the key is not be defined in `mbed_config.h` and does not affect the application or OS unless it is overridden. See `param2` and `param5` for examples of this. The JSON fragment above defines six configuration parameters named `param1`, `param2`, `param3`, `param4`, `param5` and `param6`.
`168`	`168`
`169`	`169`	Above, the configuration parameters `param1` through `param5` are defined using a description object. The description object supports the following keys:
`170`	`170`