Revert "docs: force monospace font in ASCII art (related to #3007)"

This reverts commit d1414e6.

This commit triggers a bug in po4a 0.67 (which we backported to buster
and bullseye) and 0.69 (in bookworm).

Author: SebKuzminsky

src/hal/components/toggle.comp

@@ -2,15 +2,13 @@ component toggle "'push-on, push-off' from momentary pushbuttons";
 
 description
 """
-.ie '\*[.T]'html' \{ .HTML <tt> \}
      ┐     ┌──┐        ┌──┐
 .br
 in : └─────┘  └────────┘  └──
 .br
      ┐     ┌───────────┐
 .br
 out: └─────┘           └─────
-.ie '\*[.T]'html' \{ .HTML </tt> \}
 """;
 
 pin in bit in "button input";

src/hal/components/toggle2nist.comp

@@ -11,7 +11,6 @@ and an is-on output.
 \[bu] On a rising edge on pin \\fIin\\fR when \\fIis-on\\fR is high: It sets \\fIoff\\fR until \\fIis-on\\fR becomes low.
 
 
-.ie '\*[.T]'html' \{ .HTML <tt> \}
        ┐     ┌─────xxxxxxxxxxxx┐           ┌─────xxxxxxxxxxxx┐
 .br
 in   : └─────┘     xxxxxxxxxxxx└───────────┘     xxxxxxxxxxxx└─────
@@ -28,7 +27,6 @@ off  : └──────────────────────
 .br
 is-on: └─────────────────┘                             └───────────
 
-.ie '\*[.T]'html' \{ .HTML </tt> \}
 """;
 
 pin in  bit in;