cmd/perc/main.go: try RPN parsing before percentage calculation in command mode

- Bare expressions like '1 2 +' now work without 'calc' prefix
- Assignment format 'name value =' requires 'calc' subcommand prefix

1 files changed, 4 insertions, 0 deletions

diff --git a/README.md b/README.md
index 157165d..cb7d9a5 100644
--- a/README.md
+++ b/README.md
@@ -99,6 +99,10 @@ perc calc x 5 = x x +     # x + x = 10
 
 perc calc pi 3.14159 = pi 2 *  # 2 * π
 # → 6.28318
+
+# Note: Variable assignment only works with calc/rpn subcommand:
+# perc calc x 5 = x x +  (works)
+# perc x 5 =             (won't work in bare mode - use "perc calc x 5 =")
 ```
 
 #### Variable Management