Change how birka-cli finds the tag database.

There are now two options for specifying a path, in order of precedence:
* `-o`, or `--output` command-line arguments.
* The `TB_PATH` environment variable.

1 files changed, 7 insertions, 0 deletions

diff --git a/README.md b/README.md
index 99299ef..0ece336 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,13 @@ $ birka-cli query
 ...
 ```
 
+The tag database is stored in a file, and the path of that file is dependent on
+how the program is invoked. If, when parsing the command-line arguments,
+`birka-cli` sees a `-o` or `--output` argument, the path following that argument
+will be used. Alternatively, the `TB_PATH` environment variable can be
+specified, but `-o` takes a higher precedence. If neither are specified,
+"birka.db" in the current directory is used.
+
 ### Web-Interface (API)
 
 The web interface for бирка-тян exposes a RESTful API for remotely interacting