Enable syntax highlighting in docs (#829)

Author: nene

docs/linesBetweenQueries.md

@@ -11,7 +11,7 @@ A number of empty lines. Defaults to `1`. Must be positive.
 
 ### linesBetweenQueries: 1 (default)
 
-```
+```sql
 SELECT
   *
 FROM
@@ -25,7 +25,7 @@ FROM
 
 ### linesBetweenQueries: 0
 
-```
+```sql
 SELECT
   *
 FROM
@@ -38,7 +38,7 @@ FROM
 
 ### linesBetweenQueries: 2
 
-```
+```sql
 SELECT
   *
 FROM

docs/logicalOperatorNewline.md

@@ -9,7 +9,7 @@ Decides newline placement before or after logical operators (AND, OR, XOR).
 
 ### before
 
-```
+```sql
 SELECT
   *
 FROM
@@ -22,7 +22,7 @@ WHERE
 
 ### after
 
-```
+```sql
 SELECT
   *
 FROM

docs/newlineBeforeSemicolon.md

@@ -9,7 +9,7 @@ Whether to place query separator (`;`) on a separate line.
 
 ### newlineBeforeSemicolon: false (default)
 
-```
+```sql
 SELECT
   *
 FROM
@@ -18,7 +18,7 @@ FROM
 
 ### newlineBeforeSemicolon: true
 
-```
+```sql
 SELECT
   *
 FROM

docs/tabWidth.md

@@ -11,7 +11,7 @@ This option is ignored when `useTabs` option is enabled.
 
 ### Indenting by 2 spaces (default)
 
-```
+```sql
 SELECT
   *,
 FROM
@@ -33,7 +33,7 @@ GROUP BY column4
 
 Using `indent: 4`:
 
-```
+```sql
 SELECT
     *,
 FROM
@@ -55,7 +55,7 @@ GROUP BY column4
 
 Using `indent: "\t"`:
 
-```
+```sql
 SELECT
         *,
 FROM

docs/useTabs.md

@@ -11,7 +11,7 @@ Uses TAB characters for indentation.
 
 Using `useTabs: true`:
 
-```
+```sql
 SELECT
         *,
 FROM