doc: Make it clear that store items must not be deleted by hand.

* doc/guix.texi (Invoking guix gc): Add that this is the only way to
  delete files.

1 files changed, 3 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 7ab424292e..677fc57c1a 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -1314,7 +1314,9 @@ guix package}).
 @cindex garbage collector
 Packages that are installed but not used may be @dfn{garbage-collected}.
 The @command{guix gc} command allows users to explicitly run the garbage
-collector to reclaim space from the @file{/gnu/store} directory.
+collector to reclaim space from the @file{/gnu/store} directory.  It is
+the @emph{only} way to remove files from @file{/gnu/store}---removing
+files or directories manually may break it beyond repair!
 
 The garbage collector has a set of known @dfn{roots}: any file under
 @file{/gnu/store} reachable from a root is considered @dfn{live} and