Update cheatsheets

tldr/linux/deluser

@@ -23,3 +23,7 @@ source: https://github.com/tldr-pages/tldr.git
 - Remove a user, and all files owned by them:
 
 `sudo deluser --remove-all-files {{username}}`
+
+- Remove a user from a group, without deleting the user:
+
+`sudo deluser {{username}} {{group}}`

tldr/linux/sed

@@ -27,7 +27,7 @@ source: https://github.com/tldr-pages/tldr.git
 
 - [d]elete lines 1 to 5 of a file and back up the original file with a `.orig` extension:
 
-`sed {{[-i|--in-place=]}}{{.orig}} '1,5d' {{path/to/file}}`
+`sed {{[-i|--in-place=]}}.orig '1,5d' {{path/to/file}}`
 
 - [p]rint only the first line to `stdout`:
 

tldr/linux/virt-sparsify

@@ -11,8 +11,12 @@ source: https://github.com/tldr-pages/tldr.git
 
 - Create a sparsified compressed image without snapshots from an unsparsified one:
 
-`virt-sparsify --compress {{path/to/image.qcow2}} {{path/to/image_new.qcow2}}`
+`virt-sparsify --compress {{path/to/image.qcow2}} {{path/to/new_image.qcow2}}`
 
 - Sparsify an image in-place:
 
 `virt-sparsify --in-place {{path/to/image.img}}`
+
+- Convert from one image format to another:
+
+`virt-sparsify {{path/to/image}} --convert {{qcow2|raw|vdi|...}} {{path/to/new_image}}`