fix: fill blanks and add license to flake (#35)

Author: daniqss

LICENSE.txt

@@ -631,8 +631,8 @@ to attach them to the start of each source file to most effectively
 state the exclusion of warranty; and each file should have at least
 the "copyright" line and a pointer to where the full notice is found.
 
-    <one line to give the program's name and a brief idea of what it does.>
-    Copyright (C) <year>  <name of author>
+    stepcode: specialized tool for generating static books with interactive pseudocode.
+    Copyright (C) 2026  stepcode authors
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -652,7 +652,7 @@ Also add information on how to contact you by electronic and paper mail.
   If the program does terminal interaction, make it output a short
 notice like this when it starts in an interactive mode:
 
-    <program>  Copyright (C) <year>  <name of author>
+    stepcode  Copyright (C) 2026  stepcode authors
     This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
     This is free software, and you are welcome to redistribute it
     under certain conditions; type `show c' for details.

flake.nix

@@ -1,3 +1,18 @@
+# stepcode: specialized tool for generating static books with interactive pseudocode.
+# Copyright (C) 2026  stepcode authors
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 {
   description = "stepcode";