Update documentation for Parameters

[jjant]

• Remove documentation saying \n is a valid separator, and that key/values are trimmed, as it seems this was a remnant from:

  zenoh/commons/zenoh-cfg-properties/src/lib.rs

  Lines 155 to 166 in 9d56414

  	static PROP_SEPS: &[&str] = &["\r\n", "\n", ";"];
  	const DEFAULT_PROP_SEP: char = ';';
  	const KV_SEP: &[char] = &['=', ':'];
  	const COMMENT_PREFIX: char = '#';
  	/// A map of key/value (String,String) properties.
  	///
  	/// It can be parsed from a String, using `;` or `<newline>` as separator between each properties
  	/// and `=` as separator between a key and its value. Keys and values are trimed.
  	#[non_exhaustive]
  	#[derive(Clone, PartialEq, Eq, Default)]
  	pub struct Properties(pub HashMap<String, String>);

  ,
• Mention that keys can have multiple values using | as a separator,
• Fix typo in Parameters::insert and Parameters::is_ordered: extra backtick,
• Add test/comments for Parameters::values returning empty iterator.

[github-actions]

PR missing one of the required labels: {'internal', 'api-sync', 'breaking-change', 'enhancement', 'new feature', 'ci', 'bug', 'documentation', 'dependencies'}

[jjant]

Unclear why eclipsefdn/eca is still failing, I've signed the ECA and linked my GH account in Eclipse.

Maybe the action just needs to be re-ran by someone that has permissions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.20%. Comparing base (66c3403) to head (ad857cd).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2195      +/-   ##
==========================================
- Coverage   71.32%   71.20%   -0.13%     
==========================================
  Files         375      375              
  Lines       60949    60953       +4     
==========================================
- Hits        43474    43399      -75     
- Misses      17475    17554      +79     

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