Add documentation for inequality constraints with tolerance (#907)

* Add documentation to inequality constraints with tolerance

* Update docs/articles/nunit/writing-tests/constraints/GreaterThanOrEqualConstraint.md

---------

Co-authored-by: Sean Killeen <[email protected]>

docs/articles/nunit/writing-tests/constraints/GreaterThanConstraint.md

@@ -21,6 +21,7 @@ Is.Positive // Equivalent to Is.GreaterThan(0)
 ...Using(IComparer comparer)
 ...Using<T>(IComparer<T> comparer)
 ...Using<T>(Comparison<T> comparer)
+...Within(object tolerance)
 ```
 
 ## Examples of Use
@@ -29,4 +30,5 @@ Is.Positive // Equivalent to Is.GreaterThan(0)
 Assert.That(7, Is.GreaterThan(3));
 Assert.That(myOwnObject, Is.GreaterThan(theExpected).Using(myComparer));
 Assert.That(42, Is.Positive);
+Assert.That(myDateTime, Is.GreaterThan(expectedDateTime).Within(TimeSpan.FromSeconds(1)))
 ```

docs/articles/nunit/writing-tests/constraints/GreaterThanOrEqualConstraint.md

@@ -21,6 +21,7 @@ Is.AtLeast(object expected)
 ...Using(IComparer comparer)
 ...Using<T>(IComparer<T> comparer)
 ...Using<T>(Comparison<T> comparer)
+...Within(object tolerance)
 ```
 
 ## Examples of Use
@@ -31,4 +32,5 @@ Assert.That(7, Is.AtLeast(3));
 Assert.That(7, Is.GreaterThanOrEqualTo(7));
 Assert.That(7, Is.AtLeast(7));
 Assert.That(myOwnObject, Is.GreaterThanOrEqualTo(theExpected).Using(myComparer));
+Assert.That(myDateTime, Is.GreaterThanOrEqualTo(expectedDateTime).Within(TimeSpan.FromSeconds(1)))
 ```

docs/articles/nunit/writing-tests/constraints/LessThanConstraint.md

@@ -21,6 +21,7 @@ Is.Negative // Equivalent to Is.LessThan(0)
 ...Using(IComparer comparer)
 ...Using<T>(IComparer<T> comparer)
 ...Using<T>(Comparison<T> comparer)
+...Within(object tolerance)
 ```
 
 ## Examples of Use
@@ -29,4 +30,5 @@ Is.Negative // Equivalent to Is.LessThan(0)
 Assert.That(3, Is.LessThan(7));
 Assert.That(myOwnObject, Is.LessThan(theExpected).Using(myComparer));
 Assert.That(-5, Is.Negative);
+Assert.That(myDateTime, Is.LessThan(expectedDateTime).Within(TimeSpan.FromSeconds(1)))
 ```

docs/articles/nunit/writing-tests/constraints/LessThanOrEqualConstraint.md

@@ -21,6 +21,7 @@ Is.AtMost(object expected)
 ...Using(IComparer comparer)
 ...Using<T>(IComparer<T> comparer)
 ...Using<T>(Comparison<T> comparer)
+...Within(object tolerance)
 ```
 
 ## Examples of Use
@@ -31,4 +32,5 @@ Assert.That(3, Is.AtMost(7));
 Assert.That(3, Is.LessThanOrEqualTo(3));
 Assert.That(3, Is.AtMost(3));
 Assert.That(myOwnObject, Is.LessThanOrEqualTo(theExpected).Using(myComparer));
+Assert.That(myDateTime, Is.LessThanOrEqualTo(expectedDateTime).Within(TimeSpan.FromSeconds(1)))
 ```