Merge branch 'jn/notes-doc' into maint

* jn/notes-doc: Documentation/notes: nitpicks Documentation/notes: clean up description of rewriting configuration Documentation/notes: simplify treatment of default display refs Documentation/log: add a CONFIGURATION section Documentation/notes: simplify treatment of default notes ref Documentation/notes: add configuration section Documentation/notes: describe content of notes blobs Documentation/notes: document format of notes trees