make all: document targets for RIOT base module

[mguetschow]

Contribution description

There is no target similar to make help available when calling make from the RIOT base directory, although there are several useful targets that are supposed to be called from there. Instead of adding a new help target, this PR lists the available targets manually in the welcome message.

Testing procedure

With these changes, make or make all from the RIOT base directory gives:

Welcome to RIOT - The friendly OS for IoT!

You executed 'make' from the base directory.
Usually, you should run 'make' in your application's directory instead.

Please see our Quick Start Guide at:
    https://doc.riot-os.org/getting-started.html
You can ask questions or discuss with other users on our forum:
    https://forum.riot-os.org

Available targets for the RIOT base directory include:
 generate-{board,driver,example,module,pkg,test}
 info-{applications,boards,emulated-boards} info-applications-supported-boards
 print-versions
 clean distclean pkg-clean
 doc doc-{man,latex}

make: *** [Makefile:7: all] Error 1

[benpicco]

Nice idea, thank you!

[riot-ci]

Murdock results

✔️ PASSED

f33662a make all: document targets for RIOT base module

Success	Failures	Total	Runtime
1	0	1	55s

Artifacts

• Documentation preview