Merge pull request #300 from ven-k/patch-1

docs: use `t_nounits` as `t`

Author: ChrisRackauckas

docs/src/connectors/sign_convention.md

@@ -60,6 +60,7 @@ The flow variable (i.e. force) input component for the `Mechanical` domain is
 ```@example sign_convention
 using ModelingToolkit
 using ModelingToolkitStandardLibrary.Mechanical.Translational
+using ModelingToolkit: t_nounits as t
 
 @mtkmodel ConstantForce begin
     @parameters begin