[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.