Add links for Condition functions

Author: ghogen

docs/msbuild/item-functions.md

@@ -96,6 +96,10 @@ The following example shows how to use intrinsic item functions.
   -->
 ```
 
+## MSBuild condition functions
+
+The functions `Exists` and `HasTrailingSlash` are not item functions. They are available for use with the `Condition` attribute. See [MSBuild conditions](msbuild-conditions.md).
+
 ## See also
 
 - [Items](../msbuild/msbuild-items.md)

docs/msbuild/msbuild-conditions.md

@@ -10,6 +10,8 @@ dev_langs:
 helpviewer_keywords:
 - MSBuild, conditions
 - conditions [MSBuild]
+- Exists, MSBuild condition function
+- HasTrailingSlash, MSBuild condition function
 ms.assetid: 9d7aa308-b667-48ed-b4c9-a61e49eb0a85
 author: ghogen
 ms.author: ghogen

docs/msbuild/property-functions.md

@@ -334,6 +334,10 @@ Output:
 -->
 ```
 
+## MSBuild condition functions
+
+The functions `Exists` and `HasTrailingSlash` are not property functions. They are available for use with the `Condition` attribute. See [MSBuild conditions](msbuild-conditions.md).
+
 ## See also
 
 - [MSBuild properties](../msbuild/msbuild-properties.md)