Fix typographical errors in .md files found by cspell

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>

docs/architecture/psa-crypto-implementation-structure.md

@@ -1,4 +1,4 @@
-PSA Cryptograpy API implementation and PSA driver interface
+PSA Cryptography API implementation and PSA driver interface
 ===========================================================
 
 ## Introduction

docs/architecture/psa-migration/psa-limitations.md

@@ -171,7 +171,7 @@ match a limitation of the PSA API.
 
 It is unclear what parameters people use in practice. It looks like by default
 OpenSSL picks saltlen = keylen - hashlen - 2 (tested with openssl 1.1.1f).
-The `certool` command provided by GnuTLS seems to be picking saltlen = hashlen
+The `certtool` command provided by GnuTLS seems to be picking saltlen = hashlen
 by default (tested with GnuTLS 3.6.13). FIPS 186-4 requires 0 <= saltlen <=
 hashlen.
 

docs/architecture/psa-migration/strategy.md

@@ -42,9 +42,9 @@ are:
   - When `MBEDTLS_PSA_CRYPTO_C` is enabled and used, applications need to call
     `psa_crypto_init()` before TLS/X.509 uses PSA functions. (This prevents us
 from even enabling the option by default.)
-  - `MBEDTLS_PSA_CRYPTO_C` has a hard depend on `MBEDTLS_ENTROPY_C ||
+  - `MBEDTLS_PSA_CRYPTO_C` has a hard dependency on `MBEDTLS_ENTROPY_C ||
     MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG` but it's
-    currently possible to compilte TLS and X.509 without any of the options.
+    currently possible to compile TLS and X.509 without any of the options.
     Also, we can't just auto-enable `MBEDTLS_ENTROPY_C` as it doesn't build
     out of the box on all platforms, and even less
     `MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG` as it requires a user-provided RNG