Incomplete documentation for /save and /load commands

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue
- [x] I have run `q doctor` in the affected terminal session
- [x] I have run `q restart` and replicated the issue again

### Operating system

Linux 6.6.87.2-microsoft-standard-WSL2 - Kali GNU/Linux Rolling

### Expected behaviour

The documentation should provide complete information about conversation saving/loading:

**For /save command:**
- Requires a filename parameter (not optional)
- Supports both relative and absolute paths
- Parent directories must exist beforehand (no automatic creation)
- Clear examples of valid usage patterns
- Information about default storage location
- File format and extension details

**For /load command:**
- How it interacts with saved files
- Path resolution behavior
- Error handling when files don't exist

**General:**
- Where conversations are stored by default
- File naming conventions and recommendations
- Cross-platform path handling differences if any

### Actual behaviour

Current documentation only shows basic usage:
- "/save" and "/save name"
- "/load" shows interactive selection
- Missing critical details about path handling, directory requirements, and storage behavior
- Users must discover behavior through trial and error

```
[chat-transcript]
Die Dokumentation enthält keine spezifischen Informationen darüber, wo die mit `/save` gespeicherten Konversationen abgelegt werden. Diese Details sind in der verfügbaren Dokumentation nicht dokumentiert.

Du könntest versuchen, das herauszufinden, indem du:

1. Eine Konversation speicherst: `/save test`
2. Dann nach den Dateien suchst, z.B. mit: `find ~ -name "*test*" -type f 2>/dev/null`

Oder

(...truncated)
```

### Steps to reproduce

1. Check Q CLI documentation for /save command details
2. Try to understand where files are saved and what path formats work
3. Attempt to save to non-existent directory path
4. Notice lack of clear guidance on expected behavior and requirements

### Environment

```yaml

[q-details]
version = "1.19.6"
hash = "5b649e6f65a0035ad9ee2dbad6c6b7fdb3ddf0c6"
date = "2025-11-13T18:11:44.622413Z (6d ago)"

[system-info]
chip = "12th Gen Intel(R) Core(TM) i7-12800H"
total-cores = 5
memory = "47.05 GB"

[system-info.os.linux]
kernel_version = "6.6.87.2-microsoft-standard-WSL2"
id = "kali"
name = "Kali GNU/Linux"
pretty_name = "Kali GNU/Linux Rolling"
version_id = "2025.4"
version = "2025.4"

[environment]
cwd = "/home/USER"
cli-path = "/home/USER"
install-method = "unknown"
in-wsl = true

[env-vars]
DISPLAY = ":0"
SHELL = "/bin/bash"
TERM = "xterm-256color"

[chat-settings]

[chat-trusted_tools]

[chat-failed_request_ids]
none

[chat-context]
current_profile=q_cli_default
profile_context=
AmazonQ.md
AGENTS.md
README.md
.amazonq/rules/**/*.md

files=none
```