directives do not allow arguments without values (booleans)

[ssbarnea]

Describe the bug

context

I observed that boolean arguments that do not require a value on directives do not work with myst-parser, even if they do work well with rst.

expectation

```{command-output} bash --version
   :cwd: ..
   :returncode: 2
   :nostderr:
```

workaround

Apparently adding a true as value appears to be working, but I am not 100% sure.

```{command-output} bash --version
   :cwd: ..
   :returncode: 2
   :nostderr: true
```

problem

This is problematic, especially for people doing rst2myst conversions.

Reproduce the bug

```{command-output} bash --version
   :cwd: ..
   :returncode: 2
   :nostderr:
```

List your environment

To my surprise this issue appears to happen only on Linux. On MacOS it did work as expected.

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[mmcky]

@ssbarnea I noticed you have indented the options (similar to rst)

Could you try:

```{command-output} bash --version
:cwd: ..
:returncode: 2
:nostderr:
```

or using the alternative syntax for listing groups of options

```{command-output} bash --version
---  
cwd: ..
returncode: 2
nostderr:
----
```

[ssbarnea]

In fact that was likely the result of conversion script. If that proves to work we should file a bug with it as I bet others will face similar confusions when migrating from rst.

[mmcky]

@ssbarnea I mainly want to rule that out as a source of possible issue.

[chrisjsewell]

Closing this, since it does work, see e.g.

test.md

```{contents}
:local:
```

# Heading

$ myst-docutils-pseudoxml test.md
<document source="test.md">
    <topic classes="contents local" ids="contents" names="contents">
        <bullet_list>
            <list_item>
                <paragraph>
                    <reference ids="toc-entry-1" refid="heading">
                        Heading
    <section ids="heading" names="heading">
        <title refid="toc-entry-1">
            Heading

In fact that was likely the result of conversion script. If that proves to work we should file a bug with it as I bet others will face similar confusions when migrating from rst.

FYI, there is https://github.com/executablebooks/rst-to-myst for that