Some formatting and editorial nits (#1200)

* typo

* must-to-shall

* formatting nit

* formatting nit

standard/classes.md

@@ -2299,7 +2299,7 @@ A parameter declared with an `out` modifier is an ***output parameter***. For de
 
 A method declared as a partial method ([§15.6.9](classes.md#1569-partial-methods)) shall not have output parameters.
 
-> *Note: Output parameters are typically used in methods that produce multiple return values. *end note*
+> *Note*: Output parameters are typically used in methods that produce multiple return values. *end note*
 <!-- markdownlint-disable MD028 -->
 
 <!-- markdownlint-enable MD028 -->

standard/conversions.md

@@ -507,7 +507,7 @@ An unboxing conversion permits a *reference_type* to be explicitly converted to
 - From the type `object` to any *value_type*.
 - From the type `System.ValueType` to any *value_type*.
 - From the type `System.Enum` to any *enum_type*.
-- From any *interface_type* to any *non-nullable_value_type* that implements the *interface_type*.
+- From any *interface_type* to any *non_nullable_value_type* that implements the *interface_type*.
 - From any *interface_type* `I` to any *non_nullable_value_type* where there is an unboxing conversion from an *interface_type* `I₀` to the *non_nullable_value-type* and an identity conversion from `I` to `I₀`.
 - From any *interface_type* `I` to any *non_nullable_value_type* where there is an unboxing conversion from an *interface_type* `I₀` to the *non_nullable_value_type* and either either `I₀` is variance_convertible to `I` or `I` is variance-convertible to `I₀` ([§18.2.3.3](interfaces.md#18233-variance-conversion)).
 - From any *reference_type* to any *nullable_value_type* where there is an unboxing conversion from *reference_type* to the underlying *non_nullable_value_type* of the *nullable_value_type*.

standard/structs.md

@@ -238,7 +238,7 @@ Assignment to a variable of a struct type creates a *copy* of the value being as
 
 Similar to an assignment, when a struct is passed as a value parameter or returned as the result of a function member, a copy of the struct is created. A struct may be passed by reference to a function member using a by-reference parameter.
 
-When a property or indexer of a struct is the target of an assignment, the instance expression associated with the property or indexer access shall be classified as a variable. If the `instance` expression is classified as a value, a compile-time error occurs. This is described in further detail in [§12.21.2](expressions.md#12212-simple-assignment).
+When a property or indexer of a struct is the target of an assignment, the instance expression associated with the property or indexer access shall be classified as a variable. If the instance expression is classified as a value, a compile-time error occurs. This is described in further detail in [§12.21.2](expressions.md#12212-simple-assignment).
 
 ### 16.4.5 Default values
 

standard/types.md

@@ -729,7 +729,7 @@ There are two forms of nullability for reference types:
 
 > *Note:* The types `R` and `R?` are represented by the same underlying type, `R`. A variable of that underlying type can either contain a reference to an object or be the value `null`, which indicates “no reference.” *end note*
 
-The syntactic distinction between a *nullable reference type* and its corresponding *non-nullable reference type* enables a compiler to generate diagnostics. A compiler must allow the `?` annotation as defined in [§8.2.1](types.md#821-general). The diagnostics must be limited to warnings. Neither the presence or absence of nullable annotations, nor the state of the nullable context can change the compile time or runtime behavior of a program except for changes in any diagnostic messages generated at compile time.
+The syntactic distinction between a *nullable reference type* and its corresponding *non-nullable reference type* enables a compiler to generate diagnostics. A compiler shall allow the `?` annotation as defined in [§8.2.1](types.md#821-general). The diagnostics shall be limited to warnings. Neither the presence or absence of nullable annotations, nor the state of the nullable context can change the compile time or runtime behavior of a program except for changes in any diagnostic messages generated at compile time.
 
 ### 8.9.2 Non-nullable reference types