False documentation for parameters

[orhun]

Describe the bug
Current regex for parsing the documentation gives false results sometimes.

To reproduce

Here is a few examples:

$ systeroid -E fs.mount-max

mount-max
=========
This denotes the maximum number of mounts that may exist
in a mount namespace.

# rest is irrelevant

2. /proc/sys/fs/binfmt_misc
===========================
# ...

$ systeroid -E net.mptcp.enabled

# completely irrelevant

seg6_enabled - BOOL
===================
Accept or drop SR-enabled IPv6 packets on this interface.
# ...

Expected behavior
Correct part of the documentation is parsed for the given parameter.

Screenshots / Logs
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Software information

• Operating system: Arch GNU/Linux x86_64 5.17.1-arch1-1
• Rust version: rustc 1.62.0-nightly (8f36334ca 2022-04-06)
• Project version: 0.1.0-rc.1

Additional context
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