✏️ Update README

Author: astropenguin

README.md

@@ -1,2 +1,52 @@
-# fobs
+# :globe_with_meridians: fobs
 Convert 45m/ASTE obstable to one for FMLO observation
+
+## Installation
+
+```
+$ pip install fobs
+```
+
+Note that Python 3.6 or higher is required for fobs.
+
+## Command line interface
+
+Command line interface `fobs` is available after installation.
+
+```
+$ fobs -h
+fobs: convert 45m/ASTE obstable to one for FMLO observation.
+
+Usage:
+  fobs <obstable> <actions> [<substitution>...] [options]
+  fobs -h | --help
+  fobs -v | --version
+
+Arguments:
+  <obstable>         Path of 45/ASTE obstable (*.start)
+  <actions>          Path of YAML file that describes actions.
+  <substitution>...  String(s) of substitution statement like
+                     param=value. This will replace string of
+                     <param> with value in the converted obstable.
+
+Options:
+  -h --help        Show the help and exit.
+  -v --version     Show the version and exit.
+  -f --force       Force to overwrite existing obstable.
+  -o --out <path>  Path of converted obstable. If not spacified (default),
+                   then string of it will be printed to standard output.
+  -l --log <path>  Path of log file. If not spacified (default),
+                   then log strings will be printed to standard output.
+```
+
+### Actions
+
+#### Replace
+
+#### Insert
+
+#### Delete
+
+#### Swap
+
+### Substitutions