Document the "tap-macro-release" button.

This button was undocumented but is useful.  Added it to the tutorial
and the reference.

doc/quick-reference.md

@@ -195,7 +195,8 @@ preferences—that's why there are so many! Particularly when using
 home-row modifiers, you will find some of the more crazy seeming buttons
 to be the most comfortable.
 
-+ `tap-macro`: take a sequence of keys and tap them
++ `tap-macro`: take a sequence of keys and tap them, but don’t release
+ the last key until the button is released.
 
  ```clojure
  (defalias ta1 (tap-macro K M o n a d))
@@ -211,6 +212,13 @@ to be the most comfortable.
  )
  ```
 
++ `tap-macro-release`: like `tap-macro` but don’t press the last key
+ until the button is released.
+
+ ```clojure
+ (defalias ta2 (tap-macro-release K M o n a d))
+ ```
+
 + `multi-tap`: combine a sequence of keys into one key with a timeout
  between each key, as well as a last (default) button without a delay.
 

keymap/tutorial.kbd

@@ -500,6 +500,13 @@
 
  (tap-macro K P5 M P5 o P5 n P5 a P5 d)
 
+ The `tap-macro-release` is like `tap-macro`, except that it
+ waits to press the last button when the `tap-macro-release`
+ gets released. It might be useful when combined with a
+ footswitch that sends keybooard scan codes.
+
+ (tap-macro-release i K M o n a d esc)
+
  WARNING: DO NOT STORE YOUR PASSWORDS IN PLAIN TEXT OR IN YOUR KEYBOARD
 
  I know it might be tempting to store your password as a macro, but there are 2
@@ -520,11 +527,12 @@
  mc2 #(C-c P50 A-tab P50 C-v) ;; Careful, this might do something
  mc3 #(P200 h P150 4 P100 > < P50 > < P20 0 r z 1 ! 1 ! !)
  mc4 (tap-macro a (pause 50) @md2 (pause 50) c)
- mc5 #(@mc3 spc @mc3 spc @mc3)
+ mc5 (tap-macro-release esc esc esc)
+ mc6 #(@mc3 spc @mc3 spc @mc3)
 )
 
 (deflayer macro-test
- _ @mc1 @mc2 @mc3 @mc4 @mc5 _  _ _ _ _ _ _ _
+ _ @mc1 @mc2 @mc3 @mc4 @mc5 @mc6 _ _ _ _ _ _ _
  _ _ _ _ _ _ _ _ _ _ _ _ _ _
  _ _ _ _ _ _ _ _ _ _ _ _ _
  _ _ _ _ _ _ _ _ _ _ _ _