*sum: update pages to make them consistent (#10136)

* *sum: update pages to make them consistent

* md5sum: fix typo, shasum: change 'the' to 'a' for consistency

pages/common/sha512sum.md

@@ -3,19 +3,19 @@
 > Calculate SHA512 cryptographic checksums.
 > More information: <https://www.gnu.org/software/coreutils/manual/html_node/sha2-utilities.html>.
 
-- Calculate the SHA512 checksum for a file:
+- Calculate the SHA512 checksum for one or more files:
 
-`sha512sum {{path/to/file}}`
-
-- Calculate SHA512 checksums for multiple files:
-
-`sha512sum {{path/to/file1}} {{path/to/file2}}`
+`sha512sum {{path/to/file1 path/to/file2 ...}}`
 
 - Calculate and save the list of SHA512 checksums to a file:
 
-`sha512sum {{path/to/file1}} {{path/to/file2}} > {{path/to/file.sha512}}`
+`sha512sum {{path/to/file1 path/to/file2 ...}} > {{path/to/file.sha512}}`
 
-- Read a file of SHA512 sums and verify all files have matching checksums:
+- Calculate a SHA512 checksum from `stdin`:
+
+`{{some_command}} | sha512sum`
+
+- Read a file of SHA512 sums and filenames and verify all files have matching checksums:
 
 `sha512sum --check {{path/to/file.sha512}}`
 
@@ -23,6 +23,6 @@
 
 `sha512sum --check --quiet {{path/to/file.sha512}}`
 
-- Only show a message for files for which verification fails, ignoring missing files:
+- Only show a message when verification fails, ignoring missing files:
 
 `sha512sum --ignore-missing --check --quiet {{path/to/file.sha512}}`