Document the significance of "This API has not yet reached stability" in gcr/gcr.h
When an attempt is made to include gcr/gcr.h or gcr/gcr-base.h, compilation is forced to fail as follows:
/usr/include/gcr-3/gcr/gcr-base.h:24:2: error: #error <gcr/This API has not yet reached stability.>
24 | #error <gcr/This API has not yet reached stability.>
| ^~~~~
Obviously the workaround is to declare GCR_API_SUBJECT_TO_CHANGE, however there is no link to any documentation anywhere describing when the API is likely to become stable, whether a different stable API should be used instead of this one, etc.
Please update the header file to link to an explanation of what the correct way is to use this API.
This warning was first added to the code in 2009, is this stale advice, or is this still correct in 2022?