doc: flpr and building for nrf54l15

[annwoj]

Adds building article
Adds FLPR intro

[NordicBuilder]

CI Information

^{To view the history of this post, clich the 'edited' button above}
Build number: 26

Inputs:

Sources:

more details

Github labels

Enabled	Name	Description
	ci-disabled	Disable the ci execution
	ci-all-test	Run all of ci, no test spec filtering will be done
	ci-force-downstream	Force execution of downstream even if twister fails
	ci-run-twister	Force run twister
	ci-run-zephyr-twister	Force run zephyr twister

List of changed files detected by CI (0)

Outputs:

Toolchain

Version:
Build docker image:

Test Spec & Results: ✅ Success; ❌ Failure; 🟠 Queued; 🟡 Progress; ◻️ Skipped; ⚠️ Quarantine

• ◻️ Toolchain
• ◻️ Build twister
• ◻️ Integration tests

Note: This message is automatically posted and updated by the CI

[NordicBuilder]

You can find the documentation preview for this PR at this link. It will be updated about 10 minutes after the documentation build succeeds.

Note: This comment is automatically posted by the Documentation Publishing GitHub Action.

all changes applied

[greg-fer]

The mention of VPR Launcher is confusing to me. I think it is a mistake to call a sample that uses a snippet with a proper name that suggests it is a sort of external tool. See my comments for more issues around this.

[greg-fer]

VPR launcher is a minimal sample built for an ARM core that starts given VPR core.

This is what https://github.com/zephyrproject-rtos/zephyr/blob/main/soc/nordic/common/vpr/Kconfig.sysbuild#L9-L11 from @masz-nordic states. With the comment from @wbober ("This is not a sample per se."), the Kconfig description is clearly wrong and needs to be fixed.

To be honest, I don't think we should use the name "VPR launcher" at all - not here nor in the Kconfig.
For me, the name suggests an external app or a tool. I can imagine some users will have a similar idea.
If it is a minimal sample with a snippet, it is clearly not a tool or an external app.

The current edit ("VPR launcher allows to start the FLPR core.") is unfortunately not addressing my original comment anymore because it doesn't provide a clear definition.

Please change this before merging this PR.

[greg-fer]

Three nits.