[DOC] remove repetitive words in comments

Signed-off-by: crazeteam <lilujing@outlook.com>

doc/syntax/calling_methods.rdoc

@@ -210,7 +210,7 @@ definition.  If a keyword argument is given that the method did not list,
 and the method definition does not accept arbitrary keyword arguments, an
 ArgumentError will be raised.
 
-Keyword argument value can be omitted, meaning the value will be be fetched
+Keyword argument value can be omitted, meaning the value will be fetched
 from the context by the name of the key
 
   keyword1 = 'some value'

include/ruby/internal/intern/string.h

@@ -454,7 +454,7 @@ VALUE rb_interned_str(const char *ptr, long len);
 RBIMPL_ATTR_NONNULL(())
 /**
  * Identical to  rb_interned_str(), except it  assumes the passed pointer  is a
- * pointer to a C's  string.  It can also be seen as a  routine identical to to
+ * pointer to a C's  string.  It can also be seen as a  routine identical to
  * rb_str_to_interned_str(), except  it takes a  C's string instead  of Ruby's.
  * Or it can  also be seen as a routine  identical to rb_str_new_cstr(), except
  * it returns an infamous "f"string.

spec/ruby/optional/capi/util_spec.rb

@@ -48,7 +48,7 @@ describe "C-API Util function" do
       ScratchPad.recorded.should == [1, 2, [3, 4]]
     end
 
-    it "assigns the required and optional arguments and and empty Array when there are no arguments to splat" do
+    it "assigns the required and optional arguments and empty Array when there are no arguments to splat" do
       @o.rb_scan_args([1, 2], "11*", 3, @acc).should == 2
       ScratchPad.recorded.should == [1, 2, []]
     end

test/ruby/test_string.rb

@@ -3623,7 +3623,7 @@ CODE
     assert_not_predicate +chilled_string, :frozen?
     assert_not_same chilled_string, +chilled_string
 
-    # @- the the original string as mutable
+    # @- the original string as mutable
     assert_predicate -chilled_string, :frozen?
     assert_not_same chilled_string, -chilled_string
   end

warning.rb

@@ -40,7 +40,7 @@ module Kernel
   #    baz.rb:6: warning: invalid call to foo
   #
   # If <code>category</code> keyword argument is given, passes the category
-  # to <code>Warning.warn</code>.  The category given must be be one of the
+  # to <code>Warning.warn</code>.  The category given must be one of the
   # following categories:
   #
   # :deprecated :: Used for warning for deprecated functionality that may