[ci skip] Fix docs

io.c

@@ -7524,7 +7524,7 @@ static VALUE popen_finish(VALUE port, VALUE klass);
  *
  *  - <tt>cmd[0][0]</tt> (the first string in the nested array) is the name of a program that is run.
  *  - <tt>cmd[0][1]</tt> (the second string in the nested array) is set as the program's <tt>argv[0]</tt>.
- *  - <tt>cmd[1..-1] (the strings in the outer array) are the program's arguments.
+ *  - <tt>cmd[1..-1]</tt> (the strings in the outer array) are the program's arguments.
  *
  *  Example (sets <tt>$0</tt> to 'foo'):
  *

process.c

@@ -3165,7 +3165,7 @@ NORETURN(static VALUE f_exec(int c, const VALUE *a, VALUE _));
  *  [<code>exec(cmdname, arg1, ...)</code>]
  *	command name and one or more arguments (no shell)
  *  [<code>exec([cmdname, argv0], arg1, ...)</code>]
- *	command name, argv[0] and zero or more arguments (no shell)
+ *	command name, +argv[0]+ and zero or more arguments (no shell)
  *
  *  In the first form, the string is taken as a command line that is subject to
  *  shell expansion before being executed.

struct.c

@@ -1433,12 +1433,12 @@ recursive_eql(VALUE s, VALUE s2, int recur)
  *  - <tt>other.class == self.class</tt>.
  *  - For each member name +name+, <tt>other.name.eql?(self.name)</tt>.
  *
- *    Customer = Struct.new(:name, :address, :zip)
- *    joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
- *    joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
- *    joe_jr.eql?(joe) # => true
- *    joe_jr[:name] = 'Joe Smith, Jr.'
- *    joe_jr.eql?(joe) # => false
+ *     Customer = Struct.new(:name, :address, :zip)
+ *     joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *     joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *     joe_jr.eql?(joe) # => true
+ *     joe_jr[:name] = 'Joe Smith, Jr.'
+ *     joe_jr.eql?(joe) # => false
  *
  *  Related: Object#==.
  */