doc: add note for fs.watch on virtualized env

[eljefedelrodeodeljefe]

Checklist

• tests and code linting passes
• a test and/or benchmark is included
• documentation is changed or added
• the commit message follows commit guidelines

Affected core subsystem(s)

doc

Description of change

On virtualization systems fs.watch doesn't work reliably, which is implicitly already in the respective docs. To make it more explicit this PR adds a subsentence. The following statement defers to use of fs.watchFile, which is the potential workaround.

Fixes: #6765

[cjihrig]

LGTM

[thefourtheye]

LGTM

[jasnell]

minor nit... I'd restructure the sentence just a bit...

Something like:

For example, watching files or directories can be unreliable, and in some cases impossible, on network file systems (NFS, SMB, etc), and on host file systems when using virtualization software such as Vagrant, Docker, etc. 

But I'm good with this also ;-)

[jasnell]

Left one comment but generally LGTM

[eljefedelrodeodeljefe]

Fine for me. Will adapt it before landing. Thx

[mhdawson]

I'm + 1for @jasnell's version, but generally LGTM as well.

[bnoordhuis]

s/and on/or/? I suspect most programmers are like me and interpret it boolean logic-style.

[bnoordhuis]

LGTM with a suggestion.

[eljefedelrodeodeljefe]

Went ahead and landed it in ae0f68d

Addressed both @bnoordhuis an @jasnell nits

For example, watching files or directories can be unreliable, and in some cases impossible, on network file systems (NFS, SMB, etc), or host file systems when using virtualization software such as Vagrant, Docker, etc.