Fix typos in documentation and error messages [skip ci]

CONTRIBUTING.md

@@ -45,7 +45,7 @@ on-demand.
 
 #### Don't use C++ style comments
 
-    /* This is the prefered comment style */
+    /* This is the preferred comment style */
 
 Use C++ style comments only for temporary comment e.g. commenting out some code lines.
 

mrbgems/mruby-bin-debugger/tools/mrdb/cmdmisc.c

@@ -33,7 +33,7 @@ static help_msg help_msg_list[] = {
     "\n"
     "Continue program stopped by a breakpoint.\n"
     "If N, which is non negative value, is passed,\n"
-    "proceed program until the N-th breakpoint is comming.\n"
+    "proceed program until the N-th breakpoint is coming.\n"
     "If N is not passed, N is assumed 1.\n"
   },
   {

mrbgems/mruby-fiber/src/fiber.c

@@ -167,7 +167,7 @@ fiber_switch(mrb_state *mrb, mrb_value self, mrb_int len, const mrb_value *a, mr
     }
   }
   if (resume && c->status == MRB_FIBER_TRANSFERRED) {
-    mrb_raise(mrb, E_FIBER_ERROR, "resuming transfered fiber");
+    mrb_raise(mrb, E_FIBER_ERROR, "resuming transferred fiber");
   }
   if (c->status == MRB_FIBER_RUNNING || c->status == MRB_FIBER_RESUMING) {
     mrb_raise(mrb, E_FIBER_ERROR, "double resume");
@@ -265,8 +265,8 @@ fiber_eq(mrb_state *mrb, mrb_value self)
  *  call-seq:
  *     fiber.transfer(args, ...) -> obj
  *
- *  Transfers control to reciever fiber of the method call.
- *  Unlike <code>resume</code> the reciever wouldn't be pushed to call
+ *  Transfers control to receiver fiber of the method call.
+ *  Unlike <code>resume</code> the receiver wouldn't be pushed to call
  * stack of fibers. Instead it will switch to the call stack of
  * transferring fiber.
  *  When resuming a fiber that was transferred to another fiber it would