Documentation updates

Use "encoder-decoder" rather than "encoder / decoder".

Minor limitations clarifications.

* Readme and copyright updates

* Small documentation fixes

---------

Co-authored-by: Laurence Lundblade <lgl@securitytheory.com>
diff --git a/cmd_line_main.c b/cmd_line_main.c
index 59ceb3a..4df6e98 100644
--- a/cmd_line_main.c
+++ b/cmd_line_main.c
@@ -1,5 +1,5 @@
 /*==============================================================================
-  cmd_line_mainc.c -- Runs tests for QCBOR encoder / decoder
+  cmd_line_mainc.c -- Runs tests for QCBOR encoder-decoder
 
  Copyright (c) 2018-2020, Laurence Lundblade. All rights reserved.