Feature request: Allow for adding additional message between summary and password

[martinbira]

The summary as defined in mkdocs.yml is the only way (apart from the password placeholder) on a protected page to convey a message when not logged in. As the summary replaces the <h1> tag when not logged in, leaving additional information there, such as on how to obtain a password, may look extremely bulky .

Proposition:
Allow for a configurable message to be placed within a <p> element inbetween the <h1> and the password input.

Suggested configuration:

- encryptcontent:
        message: 'Contact Support for access to this page.'

Visualisation of result:

[CoinK0in]

I add an additional information message in the extra variables.
Check README here

The changes are made in this commit: d2635a3

[martinbira]

I just gave the install a test and when starting up MkDocs it fails due to lack of BeautifulSoup, see error message below. After manually install it it runs. Perhaps it should be installed as a dependecy.

However, even though the new encryption_info_message works fine, the css_class is only applied once I'm at the locked page, not before. The prefix is still there all the time though.

PS C:\MkDocs> mkdocs serve
INFO    -  Building documentation...
Traceback (most recent call last):
  File "c:\python\python38\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "c:\python\python38\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Python\Python38\Scripts\mkdocs.exe\__main__.py", line 9, in <module>
  File "c:\python\python38\lib\site-packages\click\core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "c:\python\python38\lib\site-packages\click\core.py", line 782, in main
    rv = self.invoke(ctx)
  File "c:\python\python38\lib\site-packages\click\core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "c:\python\python38\lib\site-packages\click\core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "c:\python\python38\lib\site-packages\click\core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "c:\python\python38\lib\site-packages\mkdocs\__main__.py", line 133, in serve_command
    serve.serve(
  File "c:\python\python38\lib\site-packages\mkdocs\commands\serve.py", line 141, in serve
    config = builder()
  File "c:\python\python38\lib\site-packages\mkdocs\commands\serve.py", line 122, in builder
    config = load_config(
  File "c:\python\python38\lib\site-packages\mkdocs\config\base.py", line 197, in load_config
    errors, warnings = cfg.validate()
  File "c:\python\python38\lib\site-packages\mkdocs\config\base.py", line 107, in validate
    run_failed, run_warnings = self._validate()
  File "c:\python\python38\lib\site-packages\mkdocs\config\base.py", line 62, in _validate
    self[key] = config_option.validate(value)
  File "c:\python\python38\lib\site-packages\mkdocs\config\config_options.py", line 131, in validate
    return self.run_validation(value)
  File "c:\python\python38\lib\site-packages\mkdocs\config\config_options.py", line 609, in run_validation
    plgins[item] = self.load_plugin(item, cfg)
  File "c:\python\python38\lib\site-packages\mkdocs\config\config_options.py", line 617, in load_plugin
    Plugin = self.installed_plugins[name].load()
  File "c:\python\python38\lib\site-packages\pkg_resources\__init__.py", line 2443, in load
    return self.resolve()
  File "c:\python\python38\lib\site-packages\pkg_resources\__init__.py", line 2449, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "c:\python\python38\lib\site-packages\encryptcontent\plugin.py", line 11, in <module>
    from bs4 import BeautifulSoup
ModuleNotFoundError: No module named 'bs4'

[CoinK0in]

I fix BS4 requirement.
Please use issue #7 for css class problem.