snapshot: support ip address literals, more docs - #403

control: job assigned to worker 01M4W96AY0RWZVBRYWNNMWVCGF [factory aws, i-0644ba483de2c1335] (queued for 1 m 2 s)
...
task: starting task 0: "setup"
task: process exited: duration 4070 ms, exit code 0
...
task: starting task 1: "rust-toolchain"
task: process exited: duration 14468 ms, exit code 0
...
task: starting task 2: "authentication"
task: process exited: duration 16 ms, exit code 0
...
task: starting task 3: "clone repository"
task: process exited: duration 1529 ms, exit code 0
...
task: starting task 4: "build"
...
| 
| running 1 test
| test dpd-types/versions/src/lib.rs - (line 19) ... ignored
| 
| test result: ok. 0 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0. [...]
| 
|    Doc-tests packet
| 
| running 0 tests
| 
| test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0. [...]
| 
|    Doc-tests pcap
| 
| running 0 tests
| 
| test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0. [...]
| 
task: process exited: duration 654914 ms, exit code 0
|W| found 0 output files