Improve documentation about structure of TAR files
Clarified the segment graph description
@@ -86,8 +86,9 @@ There are four kinds of files stored in a TAR file:
catalog of blobs (i.e. value records) referenced by segments in this TAR file.
This catalog is indexed by the generation of the segments it contains.
-- graph: this file has a name ending in `.gph` and contains a representation of a
- graph. The graph is represented as an adjacency list of UUIDs.
+- graph: this file has a name ending in `.gph` and contains the segment graph
+ of all the segments in this tar file. The graph is represented as an adjacency
+ list of UUIDs.
- index: this file has a name ending in `.idx` and contains a sorted list of
every segment contained in the TAR file.
