Update storage-classes.md (#11855)

* Update storage-classes.md

Fixed the formatting issues that were incorrectly showing the variables as hyperlink texts that resulted in 404 errors

* Update storage-classes.md

Incorporated the changes

* Update storage-classes.md

removed the </strong tag that was not required.

* Update storage-classes.md

replaced <em> with `.

content/en/docs/concepts/storage/storage-classes.md

@@ -627,13 +627,13 @@ parameters:
 
 ```
 
-* `fs`: filesystem to be laid out: [none/xfs/ext4] (default: `ext4`).
+* `fs`: filesystem to be laid out: `none/xfs/ext4` (default: `ext4`).
 * `block_size`: block size in Kbytes (default: `32`).
 * `repl`: number of synchronous replicas to be provided in the form of
-  replication factor [1..3] (default: `1`) A string is expected here i.e.
+  replication factor `1..3` (default: `1`) A string is expected here i.e.
   `"1"` and not `1`.
 * `io_priority`: determines whether the volume will be created from higher
-  performance or a lower priority storage [high/medium/low] (default: `low`).
+  performance or a lower priority storage `high/medium/low` (default: `low`).
 * `snap_interval`: clock/time interval in minutes for when to trigger snapshots.
   Snapshots are incremental based on difference with the prior snapshot, 0
   disables snaps (default: `0`). A string is expected here i.e.
@@ -644,7 +644,7 @@ parameters:
 * `ephemeral`: specifies whether the volume should be cleaned-up after unmount
   or should be persistent. `emptyDir` use case can set this value to true and
   `persistent volumes` use case such as for databases like Cassandra should set
-  to false, [true/false] (default `false`). A string is expected here i.e.
+  to false, `true/false` (default `false`). A string is expected here i.e.
   `"true"` and not `true`.
 
 ### ScaleIO