remove legacy versions

Author: rustagir

config/redirects

@@ -1,7 +1,7 @@
 define: base https://www.mongodb.com/docs/php-library
 define: prefix docs/php-library
 raw: ${prefix}/ -> ${base}/current
-define: versions v1.1 v1.2 v1.3 v1.4 v1.5 v1.6 v1.7 v1.8 v1.9 v1.10 v1.11 v1.12 v1.13 v1.15 v1.16 v1.17 v1.18 v1.19 v1.20 master
+define: versions v1.16 v1.17 v1.18 v1.19 v1.20 master
 symlink: upcoming -> master
 symlink: current -> v1.20