Fix line lengths in changelog

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>

ChangeLog.d/remove_certs.txt

@@ -1,5 +1,5 @@
 API changes
    * Remove certs module from the API.
-     Transfer keys and certificates embedded in the library to the test component.
-     This contributes to minimizing library API and discourages users
-     from using unsafe keys in production.
+     Transfer keys and certificates embedded in the library to the test
+     component. This contributes to minimizing library API and discourages
+     users from using unsafe keys in production.

ChangeLog.d/remove_havege.txt

@@ -1,7 +1,9 @@
 API changes
    * Remove HAVEGE module.
-     The design of HAVEGE makes it unsuitable for microcontrollers. Platforms with a more complex
-     CPU usually have an operating system interface that provides better randomness.
-     Instead of HAVEGE, declare OS or hardware RNG interfaces with mbedtls_entropy_add_source()
-     and/or use an entropy seed file created securely during device provisioning.
-     See https://tls.mbed.org/kb/how-to/add-entropy-sources-to-entropy-pool for more information.
+     The design of HAVEGE makes it unsuitable for microcontrollers. Platforms
+     with a more complex CPU usually have an operating system interface that
+     provides better randomness. Instead of HAVEGE, declare OS or hardware RNG
+     interfaces with mbedtls_entropy_add_source() and/or use an entropy seed
+     file created securely during device provisioning. See
+     https://tls.mbed.org/kb/how-to/add-entropy-sources-to-entropy-pool for
+     more information.

ChangeLog.d/remove_old_transition_helpers.txt

@@ -1,2 +1,3 @@
 API changes
-   * Remove helpers for the transition from Mbed TLS 1.3 to Mbed TLS 2.0: the header compat-1.3.h and the script rename.pl.
+   * Remove helpers for the transition from Mbed TLS 1.3 to Mbed TLS 2.0: the
+   header compat-1.3.h and the script rename.pl.