Update canonical URLs for PHP driver docs (mongodb#1491)

Author: jmikola

README.md

@@ -22,7 +22,7 @@ extension may be found in
 ## Documentation
 
  - https://www.mongodb.com/docs/php-library/current/
- - https://www.mongodb.com/docs/drivers/php/
+ - https://www.mongodb.com/docs/drivers/php-drivers/
 
 ## Installation
 

RELEASING.md

@@ -192,7 +192,7 @@ New major and minor releases will also require documentation updates to other
 projects:
 
  * Create a DOCSP ticket to add the new version to PHP's server and language
-   [compatibility tables](https://mongodb.com/docs/drivers/php/#compatibility)
+   [compatibility tables](https://www.mongodb.com/docs/drivers/php-drivers/#compatibility)
    in the driver docs portal. See
    [mongodb/docs-ecosystem#642](https://github.com/mongodb/docs-ecosystem/pull/642)
    for an example.