Fixes x-pack/auditbeat path

[lcawl]

Related to #512

The Auditbeat Reference was failing with the following errors:

13:44:15 asciidoc: WARNING: host.asciidoc: line 8: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/host/_meta/docs.asciidoc
13:44:15 asciidoc: WARNING: host.asciidoc: line 20: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/host/_meta/data.json
13:44:15 asciidoc: WARNING: process.asciidoc: line 8: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/process/_meta/docs.asciidoc
13:44:15 asciidoc: WARNING: process.asciidoc: line 20: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/process/_meta/data.json
13:44:15 asciidoc: WARNING: socket.asciidoc: line 8: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/socket/_meta/docs.asciidoc
13:44:15 asciidoc: WARNING: socket.asciidoc: line 20: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/socket/_meta/data.json
13:44:15 asciidoc: WARNING: user.asciidoc: line 8: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/user/_meta/docs.asciidoc
13:44:15 asciidoc: WARNING: user.asciidoc: line 20: include file not found: /home/docs/docs/.repos/.temp/nUU8NVjbpg/beats/x-pack/auditbeat/module/system/user/_meta/data.json

Those files exist under x-pack/auditbeat not x-pack/auditbeat/docs, so this PR updates the path in the conf.yaml and doc_build_aliases.sh appropriately.