doc: add missing detail to env function.

* txr.1: The env function actually returns a cached list.
Spell out that the function is not required to construct a new
list.

1 files changed, 8 insertions, 0 deletions

diff --git a/txr.1 b/txr.1
index ad5aa9d5..d03525a5 100644
--- a/txr.1
+++ b/txr.1
@@ -58860,6 +58860,14 @@ contains an
 (equal) character somewhere, separating the variable name
 from its value.
 
+Multiple calls to
+.code env
+may return the same list, or lists which share structure.
+
+If a list returned by
+.code env
+is modified, the behavior is unspecified.
+
 See also: the
 .code env-hash
 function.