Add coverage badge to README.md

11 jobs for amiranda/coverage in 17 minutes and 8 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Check Format
passed #14254
check format

00:00:18

 
  Build Deps
passed #14255
compile dependencies

00:00:58

 
  Build
passed #14256
compile GekkoFS

00:05:15

passed #14257
compile tests

00:00:20

 
  Test
passed #14258
integration tests

00:09:33

passed #14261
test directories

00:00:37

passed #14263
test lseek

00:00:33

passed #14262
test truncate

00:00:34

passed #14260
test wr

00:00:39

passed #14259
unit

00:04:37

 
  Report
passed #14264
coverage

00:01:02

55.7%