add docs about the configuration

README.org

@@ -4,6 +4,16 @@
 
 ** Installation
 
+The app relies on ~AOC_SESSION~ environment variable with the session
+value from the cookie when logged in to the Advent of Code site. I
+recommend using a ~.envrc~ file and the *pass* password manager to
+store the secret : 
+
+#+BEGIN_SRC shell
+export AOC_SESSION=$(pass snamellit/advent-of-code)
+#+END_SRC
+
+
 ** Author
 
 + Peter Tillemans (pti@snamellit.com)
@@ -11,6 +21,12 @@
 ** Implementation Notes:
 
 
+*** Notable Utilities
+
+**** ~aoc:test-input <year> <day>~
+
+Fetches the test input for the given day in the given year. 
+
 *** Used dependencies
 
 
@@ -20,6 +36,9 @@ A comprehensive HTTP client library.
 
 [[https://github.com/fukamachi/dexador][GitHub repository with documentation]]
 
+The library leverages the *cl-cookie* library for cookie management.
+
+
 ** Copyright
 
 Copyright (c) 2024 Peter Tillemans (pti@snamellit.com)