Update docs for baked-in time.Duration supported tags

doc.go

@@ -321,8 +321,17 @@ equal to the parameter given. For strings, it checks that
 the string length is exactly that number of characters. For slices,
 arrays, and maps, validates the number of items.
 
+Example #1
+
 	Usage: len=10
 
+Example #2 (time.Duration)
+
+For time.Duration, len will ensure that the value is equal to the duration given
+in the parameter.
+
+	Usage: len=1h30m
+
 Maximum
 
 For numbers, max will ensure that the value is
@@ -330,8 +339,17 @@ less than or equal to the parameter given. For strings, it checks
 that the string length is at most that number of characters. For
 slices, arrays, and maps, validates the number of items.
 
+Example #1
+
 	Usage: max=10
 
+Example #2 (time.Duration)
+
+For time.Duration, max will ensure that the value is less than or equal to the
+duration given in the parameter.
+
+	Usage: max=1h30m
+
 Minimum
 
 For numbers, min will ensure that the value is
@@ -339,24 +357,51 @@ greater or equal to the parameter given. For strings, it checks that
 the string length is at least that number of characters. For slices,
 arrays, and maps, validates the number of items.
 
+Example #1
+
 	Usage: min=10
 
+Example #2 (time.Duration)
+
+For time.Duration, min will ensure that the value is greater than or equal to
+the duration given in the parameter.
+
+	Usage: min=1h30m
+
 Equals
 
 For strings & numbers, eq will ensure that the value is
 equal to the parameter given. For slices, arrays, and maps,
 validates the number of items.
 
+Example #1
+
 	Usage: eq=10
 
+Example #2 (time.Duration)
+
+For time.Duration, eq will ensure that the value is equal to the duration given
+in the parameter.
+
+	Usage: eq=1h30m
+
 Not Equal
 
 For strings & numbers, ne will ensure that the value is not
 equal to the parameter given. For slices, arrays, and maps,
 validates the number of items.
 
+Example #1
+
 	Usage: ne=10
 
+Example #2 (time.Duration)
+
+For time.Duration, ne will ensure that the value is not equal to the duration
+given in the parameter.
+
+	Usage: ne=1h30m
+
 One Of
 
 For strings, ints, and uints, oneof will ensure that the value
@@ -386,11 +431,17 @@ For time.Time ensures the time value is greater than time.Now.UTC().
 
 	Usage: gt
 
+Example #3 (time.Duration)
+
+For time.Duration, gt will ensure that the value is greater than the duration
+given in the parameter.
+
+	Usage: gt=1h30m
+
 Greater Than or Equal
 
 Same as 'min' above. Kept both to make terminology with 'len' easier.
 
-
 Example #1
 
 	Usage: gte=10
@@ -401,6 +452,13 @@ For time.Time ensures the time value is greater than or equal to time.Now.UTC().
 
 	Usage: gte
 
+Example #3 (time.Duration)
+
+For time.Duration, gte will ensure that the value is greater than or equal to
+the duration given in the parameter.
+
+	Usage: gte=1h30m
+
 Less Than
 
 For numbers, this will ensure that the value is less than the parameter given.
@@ -412,10 +470,18 @@ Example #1
 	Usage: lt=10
 
 Example #2 (time.Time)
+
 For time.Time ensures the time value is less than time.Now.UTC().
 
 	Usage: lt
 
+Example #3 (time.Duration)
+
+For time.Duration, lt will ensure that the value is less than the duration given
+in the parameter.
+
+	Usage: lt=1h30m
+
 Less Than or Equal
 
 Same as 'max' above. Kept both to make terminology with 'len' easier.
@@ -430,6 +496,13 @@ For time.Time ensures the time value is less than or equal to time.Now.UTC().
 
 	Usage: lte
 
+Example #3 (time.Duration)
+
+For time.Duration, lte will ensure that the value is less than or equal to the
+duration given in the parameter.
+
+	Usage: lte=1h30m
+
 Field Equals Another Field
 
 This will validate the field value against another fields value either within
@@ -476,9 +549,9 @@ relative to the top level struct.
 
 Field Greater Than Another Field
 
-Only valid for Numbers and time.Time types, this will validate the field value
+Only valid for Numbers, time.Duration and time.Time types, this will validate
-against another fields value either within a struct or passed in field.
+the field value against another fields value either within a struct or passed in
-usage examples are for validation of a Start and End date:
+field. usage examples are for validation of a Start and End date:
 
 Example #1:
 
@@ -490,7 +563,6 @@ Example #2:
 	// Validating by field:
 	validate.VarWithValue(start, end, "gtfield")
 
-
 Field Greater Than Another Relative Field
 
 This does the same as gtfield except that it validates the field provided
@@ -500,9 +572,9 @@ relative to the top level struct.
 
 Field Greater Than or Equal To Another Field
 
-Only valid for Numbers and time.Time types, this will validate the field value
+Only valid for Numbers, time.Duration and time.Time types, this will validate
-against another fields value either within a struct or passed in field.
+the field value against another fields value either within a struct or passed in
-usage examples are for validation of a Start and End date:
+field. usage examples are for validation of a Start and End date:
 
 Example #1:
 
@@ -523,9 +595,9 @@ to the top level struct.
 
 Less Than Another Field
 
-Only valid for Numbers and time.Time types, this will validate the field value
+Only valid for Numbers, time.Duration and time.Time types, this will validate
-against another fields value either within a struct or passed in field.
+the field value against another fields value either within a struct or passed in
-usage examples are for validation of a Start and End date:
+field. usage examples are for validation of a Start and End date:
 
 Example #1:
 
@@ -546,9 +618,9 @@ to the top level struct.
 
 Less Than or Equal To Another Field
 
-Only valid for Numbers and time.Time types, this will validate the field value
+Only valid for Numbers, time.Duration and time.Time types, this will validate
-against another fields value either within a struct or passed in field.
+the field value against another fields value either within a struct or passed in
-usage examples are for validation of a Start and End date:
+field. usage examples are for validation of a Start and End date:
 
 Example #1: