add CLI help

help.gmi

@@ -0,0 +1,33 @@
+
+```
+┏┓     •  •┳┓┓
+┃┓┏┓┏┳┓┓┏┓┓┃┃┃
+┗┛┗ ┛┗┗┗┛┗┗┻┛┗┛ v 0.1
+```
+=> https://github.com/YGGverse/gemini-dl
+
+# Usage
+
+    gemini-dl.php --source gemini://.. --target /path/to/download
+
+## Required
+
+    -s, --source     - string, gemini protocol address
+    -t, --target     - string, absolute path to destination folder
+
+## Optional
+
+    -c, --crawl      - no value, crawl document links (entire capsule download), disabled by default
+    -d, --delay      - integer, pause between requests in seconds, 1 by default
+    -i, --index      - string, index filename for directory listing, index.gmi by default
+    -h, --help       - no value, show available commands
+    -k, --keep       - no value, keep original links (--crawl mode only), disabled by default
+    -m, --match      - string, collect links match regex rule, /.*/ by default
+    -r, --raw        - no value, include meta headers (--keep option ignored), disabled by default
+    -u, --unique     - no value, append snap version as folder timestamp, disabled by default
+
+## Experimental (in development)
+
+    -e, --external   - no value, follow external hosts, disabled by default
+    -f, --follow     - integer, follow redirects on --crawl, 0 by default
+    -l, --level      - integer, depth to --crawl, 0 by default