Updating filters documentation for nested structures and maps

Author: parweza

docs/Filters.md

@@ -3,20 +3,42 @@
 Data sources that return lists of resources support filtering semantics. 
 To employ a filter include this block in your data source definition:
 
-```
+```hcl
 filter {
 	name = ""
 	values = [""]
 }
 ```
 
-The `name` value corresponds to the property name to filter with 
-and the `values` lists can contain one or more values filter with. 
+The `name` value corresponds to the qualified property name to filter with
+and the `values` lists can contain one or more values filter with.  
+
+Nested Properties and map elements can be addressed by qualifying the property name with parent property name
+Example r1 will give all the instances which have `source_type` image
+Example r2 will give all the instances which contain a defined tag with value "42" for key `CostCenter` in the namespace `Operations`
+```hcl
+data "oci_core_instances" "r1" {
+  ...
+  filter {
+    name = "source_details.source_type"
+    value = ["image"]
+  }
+}
+
+data "oci_core_instances" "r2" {
+  ...
+  filter {
+    name = "defined_tags.Operations.CostCenter"
+    value = ["42"]
+  }
+}
+
+```
 
 Multiple `values` work as an **OR** type filter. In the shape 
 example below, the resulting data source would contain both VM 
 shapes _Standard 1.1_ and _Standard 1.2_:
-```
+```hcl
 data "oci_core_shape" "t" {
   ...
   filter {
@@ -28,7 +50,7 @@ data "oci_core_shape" "t" {
 
 Multiple filters blocks can be composed to form **AND** type comparisons. The example below will return a data source containing 
 _running instances_ in the _first AD_ of a region:
-```
+```hcl
 data "oci_core_instances" "s" {
 	...
   filter {
@@ -52,8 +74,4 @@ expression special characters need to be escaped with another slash,
 shown above as the first `\` before `\w` in `"\\w*-AD-1"`.
 
 ### Limitations
-Currently filters can only target top level attributes of a 
-resource (or top level arrays of strings). 
-
-Drilling into properties of structured objects or lists of structured objects is not currently 
-supported. If these properties are targeted no results will be returned from the datasource.
+Drilling into lists of structured objects is not currently supported. If these properties are targeted no results will be returned from the datasource.