Documentation: take the sting out of the requirements

The requirements read a bit as if we only encourage coreboot experts to
try to take on these projects. These requirements should be understood
as "this is what you'll need to learn", hopefully guiding interested
people in picking a project that suits their interests.

Change-Id: I43b6e2e0df5f00e1ded8d14cee8c771e3f595ce7
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/31480
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

Documentation/contributing/project_ideas.md

@@ -13,6 +13,13 @@ should also list people interested in supporting people who want to work
 on them - since we started building this list for Google Summer of Code,
 we'll adopt its term for those people and call them mentors.
 
+The requirements for each project aim for productive work on the project,
+but it's always possible to learn them "on the job". If you have any
+doubt if you can bring yourself up to speed in a required time frame
+(e.g. for GSoC), feel free to ask in the community or the mentors listed
+with the projects. We can then try together to figure out if you're a
+good match for a project, even when requirements might not all be met.
+
 ## Provide toolchain binaries
 Our crossgcc subproject provides a uniform compiler environment for
 working on coreboot and related projects. Sadly, building it takes hours,
@@ -23,7 +30,6 @@ Windows, Mac OS. For Windows, this should also include the environment
 (shell, make, ...).
 
 ### Requirements
-
 * coreboot knowledge: Should know how to build coreboot images and where
   the compiler comes into play in our build system.
 * other knowledge: Should know how packages or installers for their