add FAQ about POSIX and C99

Author: mcpcpc

README.md

@@ -151,11 +151,12 @@ Applying a new color scheme is easy! One of the quickest ways is to use an appli
 
 ## FAQ
 
-**KISS** is an acronym for [Keep It Simple Stupid](https://en.wikipedia.org/wiki/KISS_principle), which is a design principle noted by the U.S. Navy in 1960s. The KISS principle states that most systems work best if they are kept simple rather than made complicated; therefore, simplicity should be a key goal in design, and unnecessary complexity should be avoided.
+*   **KISS** is an acronym for [Keep It Simple Stupid](https://en.wikipedia.org/wiki/KISS_principle), which is a design principle noted by the U.S. Navy in 1960s. The KISS principle states that most systems work best if they are kept simple rather than made complicated; therefore, simplicity should be a key goal in design, and unnecessary complexity should be avoided.
+*   **POSIX** is an acronym for [Portable Operating System Interface](https://opensource.com/article/19/7/what-posix-richard-stallman-explains), which is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. The *C99 Standard* is typically preferred (as opposed to C89 or C11) as this is currently the only one specified by [POSIX](https://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html).
 
 ## Known Bugs
 
-Depending on the terminal emulator, some users may experience abnormal _BACKSPACE_ key press behavior. For example, when inputting text that exceeds the width of the terminal window and wraps to a new line, the user is unable to return to editing the previous line of text.  This has been confirmed to be an [upstream issue](https://github.com/mcpcpc/kirc/issues/39) and has been reported accordingly.  While we wait for the upstream fixes, I would recommend using [urxvt](https://wiki.archlinux.org/index.php/Rxvt-unicode) or a terminal multiplexer (such as [screen](https://www.gnu.org/software/screen/) or [tmux](https://github.com/tmux/tmux/wiki)), which seemed to have resolved these issues.  
+Depending on the terminal emulator, some users may experience abnormal *BACKSPACE* key press behavior. For example, when inputting text that exceeds the width of the terminal window and wraps to a new line, the user is unable to return to editing the previous line of text.  This has been confirmed to be an [upstream issue](https://github.com/mcpcpc/kirc/issues/39) and has been reported accordingly.  While we wait for the upstream fixes, I would recommend using [urxvt](https://wiki.archlinux.org/index.php/Rxvt-unicode) or a terminal multiplexer (such as [screen](https://www.gnu.org/software/screen/) or [tmux](https://github.com/tmux/tmux/wiki)), which seemed to have resolved these issues.  
 
 ## Contact