Changed test_execd yaml due to an error in AR configuration, added do…

[jotacarma90]

…cumentation for this tests

Related issue
#1060

Description

This PR solves an error in Active Response configuration due to yaml AR section:

- tags:
  - all
  apply_to_modules:
  - test_execd_restart
  - test_execd_firewall_drop
  - conftest
  sections:
  - section: client
    elements:
    - notify_time:
        value: 10
    - time-reconnect:
        value: 60
    - auto_restart:
        value: 'yes'
    - crypto_method:
        value: 'aes'
    - server:
        elements:
        - address:
            value: SERVER_ADDRESS
        - port:
            value: REMOTED_PORT
        - protocol:
            value: PROTOCOL
  - section: active-response
    attributes:
      - name: 'active-response'
    elements:
    - disabled:
        value: 'no'

Logs example

Error due to a bad configuration:
2021/02/12 09:02:30 wazuh-execd: INFO: (1350): Active response disabled.

Tests

• Proven that tests pass when they have to pass.
• Proven that tests fail when they have to fail.

[Molter73]

LGTM!