Add conditions for each platform

[dedemorton]

Summary of changes:

• Added attributes to use for conditionally rendering commands based on the platforms supported by a Beat (this is required by Journalbeat).
• Created a separate example for each OS. We could probably continue combining deb and rpm in a single command example, but separating them gives us maximum flexibility for conditionally rendering examples in the future.
• Removed allplatforms and changed the files to use win-only to render content that's only relevant when windows is the only supported platform (currently true for Winlogbeat).
• Added attribute resets where the standalone attribute is used (resetting attributes when you no longer want them to be in scope is a best practice).
• Added attribute names to endif statements to make it easier to read the asciidoc source when there are nested conditions.

Open issues (to be addressed in future PRs):

• I still need to add linux commands. I'll do that in another PR.
• The docker commands are a bit of a mess (inconsistent coverage). It's been suggested that we remove the docker commands from the GS and point users to the topic about running on docker. I might do this, but wanted the focus of this PR to be conditional settings.

[ph]

@dedemorton I had a quick look this morning, I think the changes look OK. But I see that we are repeating a lot of the same information depending if we are in a deb/rpm/macos/ doc. Could we change the conditions to include more than one platform in the ifdef statement and reduce the duplication?

[ph]

I think you can do ifdef::deb_os,rpm_os[] example link

[dedemorton]

@ph I kind of grappled with this, too, because I don't like the repetition. I wanted to make sure that the conditional coding is granular enough to deal with situations where we might want to tag something for one OS but not the other. However, if there are two OS's that will always be supported together, then I can combine the commands. I think deb/rpm might be in this category, but I think Mac OS needs to be separate. WDYT? Linux + MacOS won't work together because Journalbeat (I believe) is linux-only, right? If you can help me identify the correct granularity for the conditions, I'll remove as much duplication as I can. My dream is to have a widget to switch between OS commands in the docs so things don't look so repetitive. (note that I haven't added the linux commands yet but I plan to)

[ph]

@dedemorton I think deb/rpm should be almost always the same. But yes you are right journalbeat is not on windows and not on mac.

[ph]

We could have a unix flavor? Looking a the doc, all of the mac, deb, rpm are similar the same.

[ph]

Looking the deb, rpm and macos commands they are pretty much the same, except that on mac you have ./ prefix to make sure we call the binaries in the current directory.

[ph]

Looking the deb, rpm and macos commands they are pretty much the same, except that on mac you have ./ prefix to make sure we call the binaries in the current directory.

[dedemorton]

@ph OK, I've merged the rpm/deb commands into single examples. For the commands in shared files (where the conditional coding is necessary), I used OR (deb_os,rpm_os) instead AND (deb_os+rpm_os). This will be weird if we ever have a Beat that supports either deb or rpm, but not both, but it avoids the situation where the command gets dropped completely if someone defines one attribute (like deb_os) but not the other.