Tweaked the style guide wording and an example (knative#3828)

* Tweaks to style docs

* Changed title case rule to upper camel case

* Tweaked webhook mutation example

docs/help/contributor/style-guide/documenting-code.md

@@ -4,16 +4,17 @@
     //todo
 
 ## Words requiring code formatting
-Use code formatting to indicate special purpose text. Apply code formatting to the following content:
+Apply code formatting only to special-purpose text:
 
-* Filenames and path names
+* Filenames
+* Path names
 * Any text that goes into a CLI
 
 ## Specify the programming language
 
-> Be sure to specify the language your code is in as part of the code block
+> Specify the language your code is in as part of the code block
 
-> Specify non-language specific code, like CLI commands, specify ```bash (see below for formatting).
+> Specify non-language specific code, like CLI commands, with ```bash (see below for formatting).
 
 === ":white_check_mark: Correct"
     ```go

docs/help/contributor/style-guide/style-and-formatting.md

@@ -1,13 +1,13 @@
 # Formatting standard and conventions
 
 ## Documenting Knative API Objects
-> Any Knative API Objects ought to use Title case.
+>  Use upper camel case for Knative API objects.
 
 |:white_check_mark: Correct                  |:no_entry: Incorrect
 |--------------------|-----
-|Channels | `Channels`
+|Channels | channels
 |Broker      | broker
-
+|ContainerSource | Container Source
 
 ## Using parentheses
 >Don’t use parentheses, unless it’s the first instance in a page to explain an acronym that isn’t immediately obvious.