add documentation on mmc linter

README.md

@@ -123,6 +123,7 @@ formatting.
 | Make | [checkmake](https://github.com/mrtazz/checkmake) |
 | Markdown | [alex](https://github.com/wooorm/alex) !!, [mdl](https://github.com/mivok/markdownlint), [prettier](https://github.com/prettier/prettier), [proselint](http://proselint.com/), [redpen](http://redpen.cc/), [remark-lint](https://github.com/wooorm/remark-lint) !!, [vale](https://github.com/ValeLint/vale), [write-good](https://github.com/btford/write-good) |
 | MATLAB | [mlint](https://www.mathworks.com/help/matlab/ref/mlint.html) |
+| Mercury | [mmc](http://mercurylang.org) !! |
 | Nim | [nim check](https://nim-lang.org/docs/nimc.html) !! |
 | nix | [nix-instantiate](http://nixos.org/nix/manual/#sec-nix-instantiate) |
 | nroff | [alex](https://github.com/wooorm/alex) !!, [proselint](http://proselint.com/), [write-good](https://github.com/btford/write-good)|

doc/ale.txt

@@ -139,6 +139,8 @@ CONTENTS                                                         *ale-contents*
       mdl.................................|ale-markdown-mdl|
       prettier............................|ale-markdown-prettier|
       write-good..........................|ale-markdown-write-good|
+    mercury...............................|ale-mercury-options|
+      mmc.................................|ale-mercury-mmc|
     nroff.................................|ale-nroff-options|
       write-good..........................|ale-nroff-write-good|
     objc..................................|ale-objc-options|
@@ -346,6 +348,7 @@ Notes:
 * Make: `checkmake`
 * Markdown: `alex`!!, `mdl`, `prettier`, `proselint`, `redpen`, `remark-lint`, `vale`, `write-good`
 * MATLAB: `mlint`
+* Mercury: `mmc`!!
 * Nim: `nim check`!!
 * nix: `nix-instantiate`
 * nroff: `alex`!!, `proselint`, `write-good`