Update naming and terminology according to the layering effort with G…

…oogle's Conversion Measurement API (#75)

* For review.

* Fixed Tess's comments.

* Changed attributeOn to attributionDestination and attributionSourceId's type to unsigned long in alignment with Tess's, Anne's, Domenic's, and John's comments.

README.md

@@ -15,13 +15,13 @@ the [Privacy Community Group](https://privacycg.github.io/).
 
 ## Introduction
 
-A popular business model for the web is to get attribution and payment for conversions, for instance purchases or sign-ups, which result from the click on an ad. Traditionally, such attribution has been facilitated by user identifying cookies sent in third-party HTTP requests to the click source. However, the same technology can be and has been used for privacy invasive cross-site tracking of users.
+A popular business model for the web is to get attribution and payment for clicks, for instance ad clicks that result in purchases or sign-ups. Traditionally, such attribution has been facilitated by user or device identifying cookies sent in cross-site HTTP requests. However, the same technology can be and has been used for privacy invasive cross-site tracking of users.
 
-The technology described [in this draft specification](https://privacycg.github.io/private-click-measurement/) is intended to allow for ad click attribution while disallowing arbitrary cross-site tracking.
+The technology described [in this draft specification](https://privacycg.github.io/private-click-measurement/) is intended to allow for click attribution, such as ad click attribution, while disallowing arbitrary cross-site tracking.
 
 ## Goals
 
-* Support ad click attribution.
+* Support click attribution across websites.
 
 * Preserve user privacy, specifically prevent cross-site tracking of users.
 
@@ -31,4 +31,6 @@ Repository: https://github.com/privacycg/private-click-measurement
 
 Link to spec: https://privacycg.github.io/private-click-measurement/
 
-Blog post with more background info: https://webkit.org/blog/8943/privacy-preserving-ad-click-attribution-for-the-web/
+Blog post with more background info: https://webkit.org/blog/11529/introducing-private-click-measurement-pcm/
+
+Original blog post with further info: https://webkit.org/blog/8943/privacy-preserving-ad-click-attribution-for-the-web/