Make false/true into builtins

Making `true` into a builtin is a significant optimization to `while
true` loops. As long as `true` is a builtin, we may as well make `false`
builtin as well (despite the fact that it's not typically executed in a
loop).

1 files changed, 10 insertions, 0 deletions

diff --git a/doc_src/true.txt b/doc_src/true.txt
new file mode 100644
index 00000000..1418c1ed
--- /dev/null
+++ b/doc_src/true.txt
@@ -0,0 +1,10 @@
+\section true true - return a successful result
+
+\subsection true-synopsis Synopsis
+\fish{synopsis}
+true
+\endfish
+
+\subsection true-description Description
+
+`true` sets the exit status to 0.