mc, jekyll, echo: add French translation and fix formatting in English version (#5000)

pages/common/jekyll.md

@@ -15,10 +15,10 @@
 
 `jekyll serve --verbose`
 
-- Generate the current directory into "./_site":
+- Generate the current directory into `./_site`:
 
 `jekyll build`
 
-- Clean the site (removes site output and cache folder) without building:
+- Clean the site (removes site output and `cache` folder) without building:
 
 `jekyll clean`

pages/common/mc.md

@@ -4,10 +4,10 @@
 > Navigate the directory structure using the arrow keys, the mouse or by typing the commands into the terminal.
 > More information: <https://midnight-commander.org>.
 
-- Start mc:
+- Start `mc`:
 
 `mc`
 
-- Start in black and white:
+- Start `mc` in black and white:
 
 `mc -b`