clarify strings include property values

Author: ghogen

docs/msbuild/msbuild-conditions.md

@@ -34,7 +34,7 @@ MSBuild supports a specific set of conditions that can be applied wherever a `Co
 |()|Grouping mechanism that evaluates to `true` if expressions contained inside evaluate to `true`.|
 |`$if$ ( %expression% ), $else$, $endif$`|Checks whether the specified `%expression%` matches the string value of the passed custom template parameter. If the `$if$` condition evaluates to `true`, then its statements are run; otherwise, the `$else$` condition is checked. If the `$else$` condition is `true`, then its statements are run; otherwise, the `$endif$` condition ends expression evaluation.<br /><br /> For examples of usage, see [Visual Studio project/item template parameter logic](https://stackoverflow.com/questions/6709057/visual-studio-project-item-template-parameter-logic).|
 
-The `Condition` element is a single string, and so any strings that are used in the expression need to be enclosed with a single-quote. Spaces between operators are allowed and commonly used for readability, but they're not required.
+The `Condition` element is a single string, and so any strings that are used in the expression, including around property values, need to be enclosed with a single-quote. Spaces between operators are allowed and commonly used for readability, but they're not required.
 
 To use the Boolean `And` and `Or` operators, specify operands inside the `Condition` element's string value, as in the following example: