Standardize VLR/EVLR notation

Author: esilvia

source/04_optional_vlrs.txt

@@ -21,7 +21,7 @@ Text Area Description
 | Record ID       | 3                           |
 +-----------------+-----------------------------+
 
-This VLR/EVLR is used for providing a textual description of the content of the
+This (E)VLR is used for providing a textual description of the content of the
 LAS file. It is a null-terminated, free-form ASCII string.
 
 .. _extrabytes_vlr_label:
@@ -212,8 +212,8 @@ Superseded
 | Record ID       | 7                           |
 +-----------------+-----------------------------+
 
-This LASF Record ID is used to negate an existing VLR/EVLR when rewriting the
-file (to remove the undesired VLR/EVLR). It is used, for example, when
+This LASF Record ID is used to negate an existing (E)VLR when rewriting the
+file (to remove the undesired (E)VLR). It is used, for example, when
 updating a record such as projection information where a new EVLR is appended
 to the end of the LAS file. The existing VLR which has been superseded must be
 marked with the SUPERSEDED Record ID.