added README section

README.txt

@@ -2,6 +2,18 @@ Remove Unused Ubuntu Kernel
 
 Purge unused Ubuntu kernels
 
+Table of Contents
+
+1.  Setup
+2.  How it works
+    1.  Script usage
+    2.  Configuration file
+    3.  How the script removes the kernels
+        1.  1stcase
+        2.  2ndcase
+        3.  3rdtcase
+3.  ToDo
+
 Setup
 
 I’ll wait for better days to come and create a proper release process.
@@ -20,13 +32,11 @@ How it works
 Script usage
 
 you can run the script using --real-run to remove the packages or use
---dry-run to show which package would have been removed.
-
-Example:
+--dry-run to show which package would have been removed:
 
     ubuntu-kernel-cleanup.py --real-run
 
-or
+or:
 
     ubuntu-kernel-cleanup.py --dry-run
 
@@ -97,3 +107,8 @@ If you use count = 2, 2 kernels will be kept:
 -   kernel5: the latest, running kernel, it will be kept
 
 the script will remove kernel1, kernel2 and kernel3
+
+ToDo
+
+-   improve algorithm to remove intermediate kernels, avoiding that in a
+    corner case you get count + 1