Fix typos in documentation (#328)

* Update README.md

* Update 0127-get-sysvar-syscall.md

* Update 0033-timely-vote-credits.md

README.md

@@ -35,7 +35,7 @@ which describes the SIMD process in detail.
 This repository is for documenting standards and not for implementation help.
 For specific questions and concerns regarding SIMDs, it's best to discuss them
 in the [questions section](https://github.com/solana-foundation/solana-improvement-documents/discussions/categories/questions)
-of this [repo's disucssion page](https://github.com/solana-foundation/solana-improvement-documents/discussions).
+of this [repo's discussion page](https://github.com/solana-foundation/solana-improvement-documents/discussions).
 
 ## Access Policy
 

proposals/0033-timely-vote-credits.md

@@ -25,7 +25,7 @@ latency".
 Vote credits are the accounting method used to determine what percentage of
 inflation rewards a validator earns on behalf of its stakers.  Currently, when
 a slot that a validator has previously voted on is "rooted", it earns 1 vote
-credit.  A "rooted" slot is one which has received full committment by the
+credit.  A "rooted" slot is one which has received full commitment by the
 validator (i.e. has been finalized).
 
 One problem with this simple accounting method is that it awards one credit

proposals/0127-get-sysvar-syscall.md

@@ -74,7 +74,7 @@ will forever have the same size.
 This prevents future upgrades that shrink or extend sysvars. In the same
 spirit, if a new sysvar is created, a new syscall must be created.
 
-Furthermore, if certain queries are requred by BPF programs - such as
+Furthermore, if certain queries are required by BPF programs - such as
 `SlotHashes::get_slot()` and `StakeHistory::get_entry()` - those single-element
 retrievals will _also_ require new syscalls.
 
@@ -83,7 +83,7 @@ It's worth noting that at the time of this writing, the work required for
 syscalls if the existing design is not ratified.
 
 This tightly-coupled relationship between sysvars and syscalls will perpetually
-swell the syscall interface as changes are made, making maintainence and
+swell the syscall interface as changes are made, making maintenance and
 reimplementation difficult.
 
 ## Alternatives Considered