pages*: fix small typos (#11850)

* pages*: fix small typos

* pages/*: make help and version commands consistent

* pages/*: follow "path/to/file" pattern

* nop: generic display help wording

pages/common/pio.md

@@ -4,7 +4,7 @@
 > Some subcommands such as `pio run` have their own usage documentation.
 > More information: <https://docs.platformio.org/en/latest/core/userguide/>.
 
-- Show help and list subcommands:
+- Display help and list subcommands:
 
 `pio --help`
 
@@ -12,6 +12,6 @@
 
 `pio --version`
 
-- Show help for a specific subcommand:
+- Display help for a specific subcommand:
 
 `pio {{subcommand}} --help`