Fix typos and add syntax highlighting to code-blocks

Recursiveness.md

@@ -1,4 +1,4 @@
-By default, `shellcheck` does not support a `-r` option. The reason for this, is that there are different matching patterns for different files.
+By default, `shellcheck` does not support a `-r` option. The reason for this is that there are different matching patterns for different files.
 
 Script could have a `.sh` extension, no extension and have a range of shebang lines (which have their own testing format):
 
@@ -10,11 +10,11 @@ Script could have a `.sh` extension, no extension and have a range of shebang li
 
 The solution for this problem is to use `shellcheck` in combination with the `find` or `grep` command.
 
-## By extension
+## By file extension
 
 To check files with one of multiple extensions:
 
-```
+```sh
 # Bash 4+
 # nullglob will prevent one of the extension patterns from appearing in the arg list
 # if they don't match.
@@ -29,9 +29,9 @@ find /path/to/scripts -type f \( -name '*.sh' -o -name '*.bash' -o -name '*.ksh'
 
 ## By shebang
 
-To check files whose shebang indicate that they are sh/bash/ksh scripts:
+To check files whose shebang indicate that they are `sh`/`bash`/`ksh` scripts:
 
-```bash
+```sh
 # POSIX
 find /path/to/scripts -type f -exec grep -Eq '^#!(.*/|.*env +)(sh|bash|ksh)' {} \; \
   | xargs shellcheck
@@ -39,7 +39,7 @@ find /path/to/scripts -type f -exec grep -Eq '^#!(.*/|.*env +)(sh|bash|ksh)' {}
 
 ## With Docker
 
-```
+```sh
 docker run --volume /path/to/scripts:/mnt koalaman/shellcheck-alpine sh -c "find /mnt -name '*.sh' | xargs shellcheck"
 ```
 
@@ -49,4 +49,4 @@ To exclude files or directories from the search(`find`) results use `! -path`. T
 
 ```sh
 find /path/to/scripts -type f \( -name '*.sh' \) ! -path '*/vendor/*' | xargs shellcheck -x -s sh
-```
+```