Fix misspellings in document

doc/api/mruby.h.md

@@ -49,7 +49,7 @@ It returns number of function retrieved.
 
 char|mruby type|retrieve types|note
 :---:|----------|--------------|---
-`o`|`Object`|`mrb_value`|Could be used to retreive any type of argument
+`o`|`Object`|`mrb_value`|Could be used to retrieve any type of argument
 `C`|`Class`/`Module`|`mrb_value`|
 `S`|`String`|`mrb_value`|
 `A`|`Array`|`mrb_value`|

doc/compile/README.md

@@ -245,7 +245,7 @@ mruby can use C++ exception to raise exception internally.
 It is called C++ ABI mode.
 By using C++ exception it can release C++ stack object correctly.
 Whenever you mix C++ code C++ ABI mode would be enabled automatically.
-If you need to enable C++ ABI mode explicity add the following:
+If you need to enable C++ ABI mode explicitly add the following:
 ```ruby
 conf.enable_cxx_abi
 ```
@@ -409,7 +409,7 @@ like this:
 
 An extra directory is created for the target platform. In case you
 compile for *i386* a directory called *i386* is created under the
-build direcotry.
+build directory.
 
 The cross compilation workflow starts in the same way as the normal
 compilation by compiling all *native* libraries and binaries.

doc/debugger/README.md

@@ -144,7 +144,7 @@ Example:
 (foo.rb:1) continue 3
 ```
 
-This will resume the profram and stop it at the third breakpoint.
+This will resume the program and stop it at the third breakpoint.
 
 #### Delete Command
 

doc/mrbconf/README.md

@@ -3,7 +3,7 @@
 ## How to use these macros.
 You can use mrbconfs with following ways:
 * Write them in `mrbconf.h`.
- * Using compiler flags is prefered  when building a cross binaries or multiple mruby binaries
+ * Using compiler flags is preferred  when building a cross binaries or multiple mruby binaries
  since it's easier to use different mrbconf per each `MRuby::Build`.
  * Most flags can be enabled by just commenting in.
 * Pass them as compiler flags.

doc/mrbgems/README.md

@@ -200,7 +200,7 @@ the following options additionally inside of your GEM specification:
 * `spec.test_objs` (Object test files for integration into mrbtest)
 * `spec.test_preload` (Initialization files for mrbtest)
 
-### include_paths and depencency
+### include_paths and dependency
 
 Your GEM can export include paths to another GEMs that depends on your GEM.
 By default, `/...absolute path.../{GEM_NAME}/include` will be exported.