RFR: Extend documentation regarding logging [v5]

[David Holmes]

On Tue, 6 Dec 2022 11:43:22 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi!
>> 
>> Here's some suggested improvements to the logging documentation. It's currently just a draft, but please feel welcome to come with any suggestions.
>
> Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove another line break

src/guide/hotspot-development.md line 21:

> 19: ~~~
> 20: 
> 21: Where 'gc' and 'marking' are tags, and 'info' is the log level. Tags associate log messages with certain subsystems or features and the log level determines the importance and verbosity of the message. The most verbose output is trace, and the least is error. The full list of tags is available [here](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/logging/logTag.hpp) and the full list of levels [here](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/logging/logLevel.hpp).

The full list of tags for a given VM is found from running `java -Xlog:help`.

src/guide/hotspot-development.md line 45:

> 43: ~~~c++
> 44: LogStream st(Log(gc, marking)::info());
> 45: if(st.is_enabled()) {

Style nits: need space after `if` (here and elsewhere).

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PR: https://git.openjdk.org/guide/pull/91