doc: add substitutions for special characters
doc: add substitutions for special characters

Add substitution patterns for (r), (tm), and (c) special symbols
via |reg| |trade| and |copy|  (same names as html entities
e.g., &reg; )

Change-Id: I0d4932435107a0bb9eef7c319c9307883e00bcb5
Signed-off-by: David B. Kinder <c56c8b29908a5b2af1b63001268d73a0b7f972ba@intel.com>

tidyjiang8/zephyr-doc,tidyjiang8/zephyr-doc,tidyjiang8/zephyr-doc,tidyjiang8/zephyr-doc,tidyjiang8/zephyr-doc