message: [Docs] Added docs on the newly supported builtin string functions
diff: | ***Name*** | ***Description*** |
  -|:----|:----:|
  -| abs() | Return the absolute value |
  -| acos() | Return the arc cosine |
  -| asin() | Return the arc sine |
  -| atan() | Return the arc tangent |
  -| cbrt() | Returns the cubic root of the argument |
  -| ceil() | Return the smallest integer value not less than the argument |
  -| cos() | Return the cosine |
  -| exp() | Raise to the power of |
  -| floor() | Return the largest integer value not greater than the argument |
  -| hypot() | Returns the hypotenuse of a right-angled triangle |
  -| log() | Return the natural logarithm of the first argument |
  -| log2() | Return the base-2 logarithm of the argument |
  -| log10() | Return the base-10 logarithm of the argument |
  -| now() | Return the current date and time |
  -| pow() | Return the argument raised to the specified power |
  -| rand32() | Return a random 32 bit interger |
  -| rand64() | Return a random 64 bit interger |
  -| round() | Round the argument |
  -| sin() | Return the sine of the argument |
  -| sqrt() | Return the square root of the argument |
  -| strcasecmp() | Compare strings without sensitivity to case |
  -| tan() | Return the tangent of the argument |
  +|:-------------|:-------------------------------------------------------------------:|
  +| abs | Return the absolute value |
  +| acos | Return the arc cosine |
  +| asin | Return the arc sine |
  +| atan | Return the arc tangent |
  +| cbrt | Return the cubic root of the argument |
  +| ceil | Return the smallest integer value not less than the argument |
  +| cos | Return the cosine |
  +| exp | Raise to the power of |
  +| floor | Return the largest integer value not greater than the argument |
  +| hypot | Return the hypotenuse of a right-angled triangle |
  +| length | Return the length of a string in bytes |
  +| left | Return the leftmost number of characters as specified |
  +| log | Return the natural logarithm of the first argument |
  +| log2 | Return the base-2 logarithm of the argument |
  +| log10 | Return the base-10 logarithm of the argument |
  +| lower | Return the argument in lowercase |
  +| lpad | Return the string argument, left-padded with the specified string |
  +| ltrim | Remove leading spaces |
  +| now | Return the current date and time |
  +| pow | Return the argument raised to the specified power |
  +| rand32 | Return a random 32 bit interger |
  +| rand64 | Return a random 64 bit interger |
  +| right | Return the specified rightmost number of characters |
  +| round | Round the argument |
  +| rpad | Append string the specified number of times |
  +| rtrim | Remove trailing spaces |
  +| sin | Return the sine of the argument |
  +| sqrt | Return the square root of the argument |
  +| strcasecmp | Compare strings without case sensitivity |
  +| substr | Return the substring as specified |
  +| tan | Return the tangent of the argument |
  +| trim | Remove leading and trailing spaces |
  +| upper | Return the argument in uppercase |
  