compiler.cfg: fix some help-lint warnings.

basis/compiler/cfg/def-use/def-use-docs.factor

@@ -6,7 +6,7 @@ HELP: defs-vregs
 { $description "Returns the sequence of vregs defined, or introduced, by this instruction." }
 { $examples
   { $example
-    "USING: compiler.cfg.def-use prettyprint ;"
+    "USING: compiler.cfg.def-use compiler.cfg.instructions compiler.cfg.registers prettyprint ;"
     "T{ ##peek f 37 D 0 0 } defs-vregs ."
     "{ 37 }"
   }
@@ -17,7 +17,7 @@ HELP: uses-vregs
 { $description "Returns the sequence of vregs used by this instruction." }
 { $examples
   { $example
-    "USING: compiler.cfg.def-use prettyprint ;"
+    "USING: compiler.cfg.def-use compiler.cfg.instructions compiler.cfg.registers prettyprint ;"
     "T{ ##replace f 37 D 1 6 } uses-vregs ."
     "{ 37 }"
   }

basis/compiler/cfg/save-contexts/save-contexts-docs.factor

@@ -12,5 +12,6 @@ HELP: bb-needs-save-context?
 { $see-also needs-save-context? } ;
 
 HELP: needs-save-context?
+{ $values { "insn" "an instruction" } { "?" "a boolean" } }
 { $description "Whether the given instruction needs to be preceeded by a " { $link ##save-context } " instruction or not. Only instructions that can allocate memory mandates save contexts." }
 { $see-also gc-map-insn } ;

basis/compiler/cfg/stacks/stacks-docs.factor

@@ -18,5 +18,5 @@ HELP: 2inputs
 { $description "Lifts the two topmost values from the datastack and stores them in virtual registers. The datastacks height is adjusted afterwards." } ;
 
 HELP: 3inputs
-{ $values { "vreg1" "a vreg" } { "vreg2" "a vreg" } { "vreg2" "a vreg" } }
+{ $values { "vreg1" "a vreg" } { "vreg2" "a vreg" } { "vreg3" "a vreg" } }
 { $description "Lifts the three topmost values from the datastack and stores them in virtual registers. The datastacks height is adjusted afterwards." } ;