Pbm tcf20 (#1887)

* added iOS purpose consent code samples

* Added GDPR purpose consent for Android

Co-authored-by: Steve <ssuranie@appnexus.com>

prebid-mobile/pbm-api/android/pbm-targeting-params-android.md

@@ -248,22 +248,47 @@ TargetingParams.addBidderToAccessControlList(TargetingParams.BIDDER_NAME_RUBICON
 
 Prebid Mobile supports the [IAB GDPR recommendations](https://www.iab.com/topics/consumer-privacy/gdpr/). For a general overview of Prebid Mobile support for GDPR, see [Prebid Mobile Guide to European Ad Inventory and Providing Notice, Transparency and Choice](/prebid-mobile/privacy-regulation.html)
 
+### Subject To GPDR
+
 Enable (true) or disable (false) the ability to provide consent.
 
+#### Retrieve subjectToGDPR
+
+```
+TargetingParams.isSubjectToGDPR();
+```
+#### Set subjectToGDPR
+
 ```
 TargetingParams.setSubjectToGDPR(context, true);
 ```
 
-Retrieve the consent string.
+### GDPR Consent String
+
+#### Retrieve gdprConsentString
 
 ```
 context = TargetingParams.getGDPRConsentString();
 ```
 
-Enable publishers to set the consent string.
+#### Set gdprConsentString
+
+```
+TargetingParams.setGDPRConsentString(string);
+```
+
+### Purpose Consent
+
+#### Retrieve purposeConsent
+
+```
+TargetingParams.getPurposeConsents();
+```
+
+#### Set purposeConsent
 
 ```
-TargetingParams.setGDPRConsentString(context, "consent_string");
+TargetingParams.setPurposeConsents(string);
 ```
 
 Prebid mobile also checks if the values are present in the [SharedPreferences](https://developer.android.com/training/data-storage/shared-preferences) keys specified by the IAB. If the values are also set in these objects they will be passed in the OpenRTB request object.

prebid-mobile/pbm-api/ios/pbm-targeting-ios.md

@@ -379,6 +379,29 @@ guard let gdprConsentString = Targeting.shared.gdprConsentString else {
 Targeting.shared.gdprConsentString = "A String"
 ```
 
+### Purpose Consent
+
+```
+public var purposeConsents: String?
+```
+
+You can retrieve and set the purposeConsents for targeting:
+
+```
+//given
+
+Targeting.shared.purposeConsents = "100000000000000000000000"
+
+defer {
+
+  Targeting.shared.purposeConsents = nil
+
+}
+
+//when
+
+let deviceAccessConsent = Targeting.shared.getDeviceAccessConsent()
+```
 ### Subject to COPPA
 
 Prebid supports passing of the Child Online Privacy Prection (COPPA) signal to Prebid Server (PBS) for all COPPA traffic. When PBS receives the COPPA flag we strip out all personal data from the requeset. For a general overview of COPPA, see the [FTC's guidlines](https://www.ftc.gov/enforcement/rules/rulemaking-regulatory-reform-proceedings/childrens-online-privacy-protection-rule).